Storage management and configuration
This chapter covers the IBM Spectrum Accelerate family, which includes IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software, storage management, and configuration by using the Hyper-Scale Manager V5.3 graphical user interface (GUI) and command-line interface (CLI) management tools. The topics include the definition of systems in the GUI and the creation of a logical configuration by using the GUI and CLI. The following topics are included:
•Creating and managing pools
•Creating and managing volumes
•Creating and managing snapshots
•Creating and managing consistency groups and snapshot groups
•Defining and managing users and user groups
Basic information about the topics is provided. This chapter also includes a section that guides you through typical scenarios that you might encounter when you manage IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software with the new GUI.
 
Important: See the following IBM Redbooks publications for information business continuity functions (mirroring, replication, and migration) and for host attachment topics:
•IBM FlashSystem A9000 and A9000R Business Continuity Solutions, REDP-5401
•IBM FlashSystem A9000, IBM FlashSystem A9000R, and IBM XIV Storage System: Host Attachment and Interoperability, SG24-8368
•FlashSystem A9000 and A9000R, XIV and Spectrum Accelerate with IBM SAN Volume Controller Best Practices, REDP-5408
2.1 Storage management interfaces
You can manage IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software deployments with the same GUI and CLI interfaces. The steps that are needed for IBM XIV Gen3, IBM FlashSystem A9000, and IBM Spectrum Accelerate are the same.
2.1.1 IBM Hyper-Scale Manager
IBM Hyper-Scale Manager is software that is installed on a server for managing and monitoring IBM storage systems. Hyper-Scale Manager reduces operational complexity and enhances capacity planning through integrated management for large and multiple-site storage system deployments. Storage administrators can use a web browser to log in to Hyper-Scale Manager and employ its advanced web-based GUI for managing and monitoring in real time, multiple IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate based storage systems.
Graphical user interface
The web-based GUI that is provided by V5.3 of Hyper-Scale Manager provides an object-centered interface design, which is aimed toward ease of use with maximum productivity for storage administrators.
The GUI is installed as part of IBM Hyper-Scale Manager. The GUI can be accessed by using a web browser and pointing to the address or URL of Hyper-Scale Manager with the port that is used to open the connection (in our case, port 8080). After Hyper-Scale Manager is installed, you are ready to define the systems to manage and start their logical configuration.
 
Note: As with any view in the GUI, the tabular view can be customized to add or remove the columns that are shown. On any view, click the title as shown in Figure 2-1, and select the options that you want to see. Each view differs, depending on the subject. The customized view can also be saved for later use.
Figure 2-1 Customize the tabular view in the GUI
2.2 Configuring pools
The concept of storage pools is purely administrative. Although the hardware resources within IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software are virtualized in a global sense, the available capacity in the system can be administratively portioned into separate and independent storage pools. Storage pools function as a virtual way to effectively manage a related group of logical volumes that are provisioned in a similar manner, consistency groups, and their snapshots.
A pool configured in IBM FlashSystem A9000 and A9000R is capacity that is virtual and not calculated on the physical or hard capacity of the system due to the data reduction techniques unique to these systems. A pool is still configured to be a specific size. However, the amount of capacity that is used depends on the pattern matching, data deduplication, and compression savings that are realized based on the data that is written from the host system.
The IBM XIV Gen3 and IBM Spectrum Accelerate software can also be reserving a physical hard capacity, in which case the pool is called regular.
The size of a storage pool can always be resized (to grow or shrink). When you are decreasing the size of a pool, the only limit is that the new pool size cannot be smaller than the total size of configured volumes in a pool or not less than the amount of data that is written to an overallocated pool.
Volumes that are not in a consistency group can be moved between storage pools without any limitations (assuming that adequate space exists in the new pool). Volumes that are part of a consistency group can be moved together as a group.
Snapshot space must be reserved during pool definition if any of the volumes in the pool will be duplicated with snapshots. This capacity is included as part of the usable capacity in the storage pool. A pool can be resized later to add or remove snapshot space, as needed.
 
Important: The space that is reserved for snapshots is not available for use by volumes.
2.2.1 Creating pools
We describe how to create storage pools by using the GUI and the CLI. Because this GUI is new, we spend additional time illustrating how this simple task is performed so that the process and views can be fully explained. The CLI is straightforward, but we included useful hints for the steps that are taken.
 
Note: Whether you create pools with the GUI or the CLI, the size that is created might differ from the size that is requested. For the IBM FlashSystem A9000 and A9000R, the created size might be larger based on a rounding-up factor to the nearest 103 GB boundary when the requested size is within 5% below that boundary. For XIV and IBM Spectrum Accelerate, the rounding up factor is based on a 17 GB boundary.
Creating pools with the GUI
The creation and resizing of storage pools are straightforward. The name of the storage pool must be unique within a system. Because Hyper-Scale Manager can have multiple systems in the inventory, the name uniqueness is still at a system level, not based on all systems that are managed by Hyper-Scale Manager.
The size of the pool must consider volumes to be added to the pool and the future activity within the storage pool (especially for snapshot propagation from creating too many snapshots). On the depletion of space in a pool, the system progressively deletes snapshots (based on a deletion priority) in the pool to clear space for additional write requests.
The system enables the assignment of the entire effective capacity to user-created storage pools. The storage pool is initially empty, and it does not contain volumes. When you create a storage pool, the size cannot be zero capacity.
To create a storage pool, complete the following steps:
1. Click the New icon in the top menu bar, and select Pool as shown in Figure 2-2.
Figure 2-2 Create New menu
2. The Create Pool wizard opens on the right side of the window, as shown in Figure 2-3. Note the red asterisk (*) icon to the right of certain field names. This asterisk indicates the required fields.
Figure 2-3 Creating a pool
3. Choose the unit of measurement, GB or TB, from the drop-down list. GB is the default setting.
4. The option to select Regular or Thin is available but will be disabled if the system selection is FlashSystem A9000 or A9000R. If Thin is selected, an additional field is displayed to select the hard size (or physical size) and the pool size (or soft size).
5. Enter the snapshot reserved size and pool size. The snapshot size can be zero if no snapshots are planned for the volumes in this pool. It can also be updated at a later time if the snapshot requirements change.
 
Snapshot size: The snapshot size is a subset of the total pool size. It does not allocate more space.
Snapshot reserve: The system preemptively deletes snapshots if the snapshots fully use the allocated space of the storage pool. Ensure that adequate space is allocated for the snapshot reserve when you define a storage pool. A preferred practice is to allocate 10% - 20% of the pool size for snapshots.
6. Enter the pool size that you want. The “i” indicates that additional information is available for this field. Hover the pointer over this i to display information about the pool size. For IBM FlashSystem A9000 and A9000R it is rounded up to 103 GB units, as shown in Figure 2-4, and for IBM XIV Gen3 and IBM Spectrum Accelerate software, it is rounded up to 17 GB units.
 
Figure 2-4 Pool size additional information
 
Note: IBM FlashSystem A9000 and A9000R use the concept of allocation unit (AU) size for volumes. The AU size is set at 103 GB. The minimum volume size that can be created is 1 GB. However, volumes that are created with a specified size within 5% less than the AU size are rounded to the AU size. For example, if you create a volume and specify a size of 98 GB, a volume of 103 GB is created on the system.
In IBM XIV Gen3 and IBM Spectrum Accelerate, the minimum volume size is 17 GB, and all volumes will be in increments of 17 GB.
7. Select the system in which you want the pool created. Click the arrow icon to show a drop-down list that displays the systems that are managed by Hyper-Scale Manager. An example of this list is shown in Figure 2-5 on page 38. Select the system from the list to close the list of systems and insert your selection in the field.
Figure 2-5 System and domain selection for pool
8. The domain selection is next, and it is also a required field. Click the arrow icon to expand the list. If the pool will not be in a domain, leave it default as /Global Space/.
If the pool will be associated with a domain, either select the domain from the list or choose Create Domain, which starts the wizard to create a domain. Refer to 4.2.1, “Creating domains” on page 115 for more details. Figure 2-5 shows an example.
The last section is only for IBM XIV Gen3 pool creation, where it is possible to choose to have compressed volumes or uncompressed volumes.
9. Two additional options are available depending on prior selections. If the system is XIV or Spectrum Accelerate and Thin has been selected, then you will have the option to select Read-only or No IO for the pool. Additionally, you can select Compressed or Uncompressed for XIV.
10. Click Create to create the pool with your specified settings, as shown in Figure 2-6. Any of these settings can be modified later, if needed.
Figure 2-6 Completed fields for a new pool
Creating pools with the command-line interface
All of the operations that are performed with a pool in the GUI can be performed with the CLI. To obtain a list of all of the pool-related commands in the CLI, enter the following command in the CLI session:
help category=storage-pool
The output of this command is shown in Figure 2-7.
Figure 2-7 Storage pool commands in the CLI
Alternatively, while you are in the CLI session, you can enter the pool_ command followed by pressing the Tab key to see all of the commands that start with these characters. The output of this command is shown in Example 2-1.
Example 2-1 All of the commands that begin with “pool_”
ITSO_2_A9000R>>pool_
pool_change_config pool_config_snapshots pool_create pool_delete pool_list
pool_rename pool_resize
To create a pool, enter the pool_create command. To see all of the options that are associated with the creation of a pool, enter the command followed by pressing the Tab key to see them, as shown in Example 2-2. Of these parameters, only three are mandatory: Pool, size, and snapshot_size. You do not need to enter the name of the system, which was required with the GUI. You are not required to enter the name with the CLI because the CLI connects directly to a single system and not through Hyper-Scale Manager.
Example 2-2 Parameters for the pool_create command
ITSO_2_A9000R>>pool_create
pool= size= snapshot_size= perf_class= domain=
The remaining fields are optional. The system administrator can use the perf_class option to associate a quality of service (QoS) performance class with the pool. The default is no performance class. To create the pool, enter the following command as shown in Example 2-3.
Example 2-3 Create a pool
ITSO_2_A9000R>>pool_create pool=itso_pool3 size=500 snapshot_size=20
In this example, we created a pool with a size of 500 GB and a snapshot reserve size of
20 GB. Other actions that can be performed on a pool, such as resizing a pool and deleting a pool, are covered in the next section.
2.2.2 Managing storage pools with the GUI
In this section, we will describe how to manage storage pools by using the GUI management tool. Managing pools with the GUI is straightforward. The related tasks can be reached through the Pools & Volumes Views and the Hub view. You can also access the pool actions from other places, such as systems and domains as well as with a right-click the pool. In this section, we use the Pools & Volumes views and then the Pools view.
Figure 2-8 shows an example of the Pools view. To manage a pool, select the specific pool and click the Actions menu (or right-click), which is shown in Figure 2-9.
Figure 2-8 Pool view
Figure 2-9 Pool actions menu
The following actions are available:
•Properties: The administrator can view and modify pool properties.
•Volumes: The administrator can view and create volumes.
•QoS: The administrator can create and remove performance classes on a pool.
•Pool Capacity: The administrator can generate capacity reports.
•Policy Controls: The administrator can view and modify pool thresholds.
•Statistics: The administrator can view performance and capacity statistics.
•Migration: The administrator can migrate volumes from another system to this pool.
•Compression: The administrator can change between compressed pool and uncompressed pool for IBM XIV Gen3.’
•Snapshot Scheduler: The administrator can setup automatic scheduled snapshots.
•Delete: The administrator can delete a pool and all of its volumes.
Properties
First, we look at the properties for a pool. The available options under Actions → Properties are shown in Figure 2-10. The storage administrator can view the properties of a pool. The storage administrator can modify the pool’s name, size and domain association. For IBM XIV Gen3 and IBM Spectrum Accelerate software the administrator can also change lock behavior.
Figure 2-10 Options for pool properties
Selecting the View Properties option, two sections are available: the Hub view and the Pool Properties. Both sections are shown in Figure 2-11. The top section is the Hub view. You can use any elements of the Hub to drill down for more information and for pool-related options, such as Belonging and QoS.
The lower section lists the pool properties. From this view, you can modify the pool attributes. All editable fields are shown in a lighter shaded area (name, snapshot size, and pool size). Changes can be made and applied by modifying the fields and clicking Apply (not shown).
Figure 2-11 shows the pool properties.
Figure 2-11 View the pool properties
Volumes
The storage administrator can use the Volumes action to view and create volumes within the pool. These options are shown in Figure 2-12.
Figure 2-12 Volumes view for a pool
The storage administrator can optionally look at the pool’s volume summary from this menu by selecting View Volumes and Belonging, which displays the Hub and Summary views as shown in Figure 2-13. The storage administrator also optionally can create snapshots of these volumes from this view by selecting NEW in the lower-right corner.
This action launches the Create Snapshot view, which is reviewed in 2.4.1, “How to create a snapshot of a volume” on page 69.
Figure 2-13 Volume summary and Belonging selected for a pool
Clicking any of the elements within the Hub will display additional details about that element in the inspector area as shown in Figure 2-13.
Figure 2-14 illustrates what the Hub and Summary view looks like on the right side of the window when you list the volumes within a pool by using this method.
Figure 2-14 Hub view of the volumes in the same pool
Quality of service (QoS)
The storage administrator can easily set or cancel a performance class to limit the traffic to a specific pool with QoS under the Actions menu as shown in Figure 2-15.
Figure 2-15 Setting QoS
By selecting the option to set QoS, you can optionally use an existing performance class or create a new performance class. When you create a performance class, the Create QoS Performance Class window opens. You must enter the name of the class and select bandwidth (BW) or input/output operations per second (IOPS) as the limiting factor. You can also specify if the performance class will be shared among all the members that are assigned this QoS or if each member will be limited individually.
Figure 2-16 shows an example of this view.
Figure 2-16 Create QoS Performance Class
Pool capacity
The storage administrator can select Pool Capacity to generate a capacity and trend forecasting report for the pool. See Figure 2-17.
Figure 2-17 Pool capacity reports
The report is generated in PDF format and saved on the system from which the browser was launched. The compressed file that contains the report is identified by the name and appended with the date and time that it was generated, as shown:
# 03/04/16 12:20 PM 69,097 capacity_planning_reports_2016-10-10_14-05-33.zip
This report requires at least 30 days of monitoring by the Hyper-Scale Manager (HSM) to generate the compressed file and includes information about system capacity, domain usage, and pool usage.
Policy controls
Policy controls are the capability to set or modify pool thresholds. You first select Pools in the Pools & Volumes Views and then select a pool in the list of pools. Under the Actions menu, or with a right-click, select Policy controls → View/Modify Pool Thresholds as shown in Figure 2-18.
Figure 2-18 Pool thresholds
After View/Modify Pool Thresholds is selected, the Pool Thresholds view of the pool’s properties is shown on the right side of the window. You can use the systemwide settings or customize the settings for this pool. When Custom Threshold is selected, as shown in Figure 2-19 on page 45, the storage administrator can adjust the percentages for each value under volumes and snapshots, and decide whether a particular notification is needed based on severity.
Figure 2-19 Customizing pool thresholds
 
Tip: The critical threshold is not set, by default. The critical threshold can easily be added if more notification is needed than the major threshold by selecting the Critical option and entering a percentage.
 
Important: Thresholds for volume usage cannot be defined for FlashSystem A9000 and A9000R running code V2.1.x or later as the volume’s physical capacity is managed at the system level. The fields will be uneditable for systems at code V12.1 or later.
Statistics
The Hyper-Scale Manager also provides you with the option to view the volumes and snapshots performance statistics and capacity statistics from the pool’s Actions menu, as shown in Figure 2-20.
Figure 2-20 Volume statistics in a pool
When selecting the performance option, the Volume Statistics view for all of the volumes within the pool is displayed, as shown in the example in Figure 2-21.
Figure 2-21 Volume statistics within a pool
 
Note: Hovering with the cursor over any point on the line in the Statistics view opens a summary for that particular point, as shown in Figure 2-22.
Figure 2-22 Summary of volume statistics within a pool
Additional information can be seen by selecting the capacity option or the snapshots option.
The storage admin can also view current and historical statistics for a single volume, as shown in Figure 2-23. This can be seen by selecting a single volume from the pool view as well as from the volumes view. You can find more information about the volume view in “Statistics” on page 74.
Figure 2-23 Statistics for a single volume
The storage administrator can view the pool usage by expanding the statistics view at the bottom of the page. An example of the expanded graph is shown in Figure 2-24. Notice the two available options to view usage as well as usage plus forecast for the selected pool’s volumes. This example is showing a range of one month.
Figure 2-24 Pool usage
Migration
This migration option within a pool is another path for the storage administrator to initiate a data migration from another system to this system. The Migrate remote Volume to Pool menu option is shown in Figure 2-25. The selection of this option opens the data migration wizard, as shown in Figure 2-26.
Figure 2-25 Migrate volumes to this pool
Figure 2-26 Volume migration wizard
Compression
A pool’s compressed state on IBM XIV Gen3 can be seen in the pool properties when a pool has been selected from the pools view. An example of this is shown in Figure 2-27.
Figure 2-27 IBM XIV Gen3 pool compression state
Only the IBM XIV Gen3 can have a mixture of uncompressed and compressed pools. To change the pool from uncompressed to compressed on the XIV Gen3 select the Compression option in the Actions menu, as shown in Figure 2-28.
Figure 2-28 Compression setting
This setting can only be changed on IBM XIV Gen3. When set, it will create new volumes with the given setting (compressed or uncompressed) as shown in Figure 2-29.
Figure 2-29 Selection Compressed or Uncompressed in IBM XIV Gen3
 
Reminder: All compressed pools in IBM XIV Gen3 must be thin provisioned.
Snapshot Scheduler
The Snapshot Scheduler is a new option available with Hyper-Scale Manager V5.3 and allows the system administrator to automate snapshots on a defined schedule. Doing this at the pool level automatically applies to existing and new volumes and consistency groups within the pool.
To work with the scheduler, select a pool in the pools view. Then, under the Actions menu, select Snapshot Scheduler. There are several options available, as shown in Figure 2-30, which are discussed in more detail in “Snapshots” on page 68.
Figure 2-30 Snapshot scheduler
Delete a pool
To delete a pool, select the pool in the Pools view. Then, under the Actions menu, select Delete → Delete Pool(s), as shown in Figure 2-31. The capacity of the deleted pool is returned to the free space (either in the global space or in a domain, depending on what the pool is associated with).
Figure 2-31 Deleting a pool
 
Note: If a pool contains volumes or consistency groups, the system does not delete the pool, but the GUI prompts you with an option to navigate to the Volumes view to delete the volumes, as shown in Figure 2-32.
Figure 2-32 Volumes and consistency groups must be deleted or moved from a pool
Optionally, you can move the volumes or consistency group to another pool instead of deleting the objects so that you can delete the pool.
2.2.3 Managing storage pools with the CLI
All of the operations that are performed with the GUI on pools can also be performed by using the CLI. A list of pool-related commands is shown in Figure 2-33. To generate this list of commands during a CLI session, enter the following command:
help category=storage-pool
Figure 2-33 Storage pool-related CLI commands
 
Note: The commands that are shown in this section are queried during a CLI session.
Not all of the commands that relate to storage pools begin with pool. However, by using the CLI in session mode, you can press the Tab key to generate the commands that begin with “pool_”, as shown in Example 2-4.
Example 2-4 Generate a list of commands that begin with “pool_”
ITSO_2_A9000R>>pool_
pool_change_config pool_config_snapshots pool_create pool_delete pool_list
pool_rename pool_resize
You can use the Tab key to complete the command if it is unique (if you entered pool_cr and then pressed the Tab key). You also can issue all of the options, for example, the available options for modifying a pool, setting QoS, setting a performance class (perf_class), changing the lock behavior, and setting the pool thresholds, within a command. All of these options are shown in Example 2-5 on page 51.
Example 2-5 Generate a list of options for a specific command
ITSO_2_A9000R>>pool_change_config
pool= lock_behavior= perf_class= code= severity= threshold=
restore_thresholds= hysteresis=
 
Tip: The options for any CLI command can be listed by entering the command followed by pressing the Tab key.
To list the pools in a system or systems, issue the pool_list command. The sample output of this command is shown in Figure 2-34.
Figure 2-34 List of pools
To create a pool, enter the following command:
pool_create pool=itso_p3 size=2050 snapshot_size=400 lock_behavior=read_only sparse=yes
The snapshot_size is a mandatory field, which must be a positive integer value (including 0). If sparse is included, the lock_behavior must be specified if the behavior that you want is not the default of read_only. If the parameter is not included, the default is applied to the pool.
Even with the CLI command, the system automatically adjusts the pool size and snapshot size, as shown in Example 2-6.
Example 2-6 Automatically adjusted size
Name Size (GB) Snap Size (GB)
itso_pool3 2067 413
Run the following command to resize an existing pool:
pool_resize pool=itso_pool3 size=5000 snapshot_size=800
Run the following command to delete a pool:
pool_delete pool=itso_pool3
Approve or deny deletion by responding y or n when you are prompted. You can also use the -y parameter with the command to approve deletion without the prompt.
 
Tip: Use the -y parameter at the end of a command that requires confirmation so that the command is automatically approved. This parameter is useful for scripting.
2.3 Volumes
IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software offer logical volumes as the basic data storage element for allocating usable storage space to attached hosts. This logical unit concept is known, and it is widely used by other storage systems and vendors. IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software facilitate the creation of volumes without planning volume layout or optimizing physical layer for performance.
Traditionally, logical volumes are defined within various Redundant Array of Independent Disks (RAID) arrays, where their segmentation and distribution are manually specified. The result is often a suboptimal distribution within and across storage modules that depends on the administrator’s knowledge and expertise.
IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software use the grid concept and distribute data evenly across flash or disk enclosures.
Within IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software, each volume is equally distributed across the flash or disk enclosures. This method dramatically simplifies storage provisioning, letting the system automatically lay out your volume in an optimal way.
2.3.1 Creating volumes
After you define the storage pools, the next logical step in system configuration is the definition of the volume. Volumes can be created with either the GUI or the CLI. Both of these methods are described in this section. However, remember that with this version of the Hyper-Scale Manager, you can start by creating a volume and be prompted to create a
new pool.
Create volumes with the GUI
To create a volume, click the NEW icon and select Volume, as shown in Figure 2-35.
Figure 2-35 Create volumes
This action opens the Create Volume view (Figure 2-36 on page 53).
You must enter the required fields as indicated by the red asterisks (*). In this window, you can also use the drop-down list to select the units for the volume, the domain, the system and the pool. If the Hyper-Scale Manager is managing multiple systems, including XIV and IBM Spectrum Accelerate, these will all be displayed in the System drop-down list. An example of the creating a new volume is shown in Figure 2-36 on page 53.
Figure 2-36 Create Volume wizard
 
Tip: The information content is displayed when you move the cursor over the i in the circle next to the field name.
After you enter the information, select Create to complete the task. The new volumes are displayed, as shown in Figure 2-37.
Figure 2-37 List of volumes
Alternatively, you can create volumes from the Pools view under Actions → Volumes → Create Volumes here as shown in “Volumes” on page 42. This action opens the same Create Volume view as shown in Figure 2-37 except that the System, Domain, and Pool fields are filled in.
Create volumes with the CLI
All of the operations that are available in the GUI can also be performed through the CLI. Remember that when using the CLI you are communicating directly to a system and do not need to specify which system in the command (as is required with the GUI). To obtain a list of all of the volume-related commands, enter the following command in a CLI session:
help category=volume
The output of this command is shown in Figure 2-38.
Figure 2-38 CLI list of volume-related commands.
Alternatively, you can obtain a list of all of the CLI commands that begin with vol by entering vol in the session, followed by pressing the Tab key twice. This action displays the commands, as shown in Example 2-7.
Example 2-7 CLI commands that begin with vol
ITSO_2_A9000R>>vol_
vol_allocation_bitmap vol_bind_list vol_clear_external_id vol_copy vol_create
vol_create_many vol_delete vol_diff vol_diff_copy vol_format
vol_list vol_list_extended vol_lock vol_mapping_list vol_move
vol_rename vol_resize vol_set_external_id vol_unlock
You can run a search on an object, such as volume, by entering the following command:
help search=volume
This command results in all of the commands that are related to volumes, including commands that are related to mapping, consistency groups, and snapshots.
To create a volume, run the following command:
vol_create vol=itso_vol7 pool=itso_pool1 size=40
The volume is logically formatted at creation time, which means that any read operation results in returning all zeros as a response. To format a volume, run the following command:
vol_format vol=itso_vol7
All of the data that is stored on the volume is lost and unrecoverable. If you want to bypass the warning message, type -y directly after the CLI command.
To list the existing volumes in a system and in a particular pool, run the following command:
vol_list pool=itso_pool2
For a list of all of the volumes in a system, run this command:
vol_list
The result of this command is similar to the output that is shown in Figure 2-39.
Figure 2-39 vol_list output
For more information, see the following resources:
•IBM FlashSystem A9000R Command-Line Interface (CLI) Reference Guide, SC27-8711
•IBM FlashSystem A9000 Command-Line Interface (CLI) Reference Guide, SC27-8559
•IBM XIV Gen3 Command-Line Interface (CLI) Reference Guide, GC27-3914
•IBM Spectrum Accelerate Command-Line Interface (CLI) Reference Guide, SC27-6697
2.3.2 Managing volumes with the GUI
To manage volumes from the Storage Management GUI, select Volumes from the Pools & Volumes Views. This option lists all of the volumes for the systems that are managed by the GUI in a single table. If you select any of the volumes in the table, you enable the Actions menu.
The available actions are listed:
•Properties: View and modify volume properties.
•Snapshots: Create, view, and restore snapshots.
•Mirror: Set up and modify volume mirroring.
•HyperSwap: define and manage HyperSwap volumes
•Mapping: View and modify volume mapping.
•Consistency Group: Move a volume to a consistency group or remove a volume from a consistency group.
•QoS: Enable or cancel a performance class with a volume.
•Pool Capacity: Create a capacity report.
•Statistics: View the performance statistics of a volume.
•Migration: Set up migration to the selected volume.
•Online Volume Mobility: Move the volume to another system of the same type.
•Volume Data: Format the volume and copy the volume.
•Compression: Compress or decompress a volume in IBM XIV Gen3.
•Delete: Delete the selected volume or volumes.
Other ways exist to navigate to volume actions, for example, from within a pool. However, in this section, we focus on the Volumes view and look at each main option under the Actions menu.
Properties
First, we look at the Properties action. By selecting this option, the storage administrator can view the properties of a volume, rename a volume, resize a volume, and change the lock state of a volume. The options are shown in Figure 2-40.
Figure 2-40 Volume properties
When View Properties is selected, the data is displayed as shown in Figure 2-41.
Figure 2-41 Volume Properties and Hub view
The volume properties are displayed on the lower half of the view in the inspector. The meter displays how much has been written by the host before compression. IBM XIV Gen3 and IBM Spectrum Accelerate display additional information about compression and reduction savings. The equivalent FlashSystem A9000 and A9000R information is managed on a system level.
The upper portion shows the Hub with all of the associated options for the volume. Circles with a solid line indicate an active association, and they can be expanded for more information. Circles with a dashed line indicate no associations with the volume. A storage administrator can click one to create an association for that volume (such as a mapping, a consistency group, or migration).
 
Note: This view is the default view that is shown when you select a volume. The view changes slightly when multiple volumes are selected.
Snapshots
The next option under the Actions menu is snapshots. This option is shown in Figure 2-42. The options include creating snapshots, viewing snapshots, and restoring the volume data from a snapshot.
Figure 2-42 Volume snapshot options
To create a snapshot of a volume in the GUI, select Create Snapshot(s). After you select this option, the view that is shown in Figure 2-43 displays on the right side of the browser window. The system will append the name of the volume with .snapshot_ or you can enter another name.
Figure 2-43 Create volume snapshot
You can then select the deletion priority for the snapshot from the drop-down list. The default deletion priority is 1 - Last. Deletion priority is described in more detail in 2.4.2, “Snapshot deletion priority” on page 71.
The snapshot is created after you click Apply. A message that indicates the success or failure of the command is displayed briefly at the bottom of the view.
 
Important: Snapshot deletion occurs automatically. Older snapshots are deleted without warning whenever a new snapshot is taken and space is needed for the new volume or snapshot data. Deletion occurs based on the deletion priority. Priority 0 - Golden Snapshot means that the snapshot will not be deleted automatically.
In addition to a single snapshot of a volume, you can create snapshots of multiple volumes. This capability is not the same as creating a snapshot of a consistency group. Snapshots are created of all of the selected volumes, but might not be consistent.
An example is shown in Figure 2-44 with the selection of the volumes.
Figure 2-44 Create multiple snapshots selection
After the volumes are selected, the Create Snapshot window opens. With multiple snapshots, you can only select the deletion priority. The name of the snapshots is generated automatically, and it can be changed later under the Snapshots view. An example of creating multiple snapshots at the same time is shown in Figure 2-45.
Figure 2-45 Create snapshots for multiple volumes at the same time
Volumes from different pools can also be selected at the same time to create snapshots. The “volume belonging” then shows the number of pools instead of the name of the pool.
 
Note: If the Inspector is maximized, you will not see the expanded view of the Belongings element in the Hub view.
For more information about snapshots, see 2.4, “Snapshots” on page 68.
Mirror
This option allows the storage administrator to create and manage mirrored volumes and is discussed in detail in IBM FlashSystem A9000 and A9000R Business Continuity Solutions, REDP-5401.
HyperSwap
This option allows the storage administrator to create and manage a HyperSwap relationship and is discussed in detail in IBM HyperSwap for IBM FlashSystem A9000 and A9000R, REDP-5434.
Mapping
Mapping volumes to a host is the next option under the Actions menu as shown in Figure 2-46. First, the storage administrator selects the volume or multiple volumes. Then, the storage administrator selects Mapping → View/Modify Mapping to display the Volume Mapping view on the right side of the window.
Figure 2-46 Mapping volumes to a host
If no mappings exist for the volumes, click the plus sign (+) to add a mapping, as shown in Figure 2-47.
Figure 2-47 Create a volume mapping
This action displays the option to select a host or a cluster, the host name, and the logical unit number (LUN) for the volume. If multiple volumes are selected for mapping, the LUN option is set to Auto. An example of mapping a single volume to a host is shown in Figure 2-48.
Figure 2-48 Volume mapping host selection
Click Apply after the required selections are made and the volumes are ready to be used by the host system. For more information about host attachment and mapping, see
IBM FlashSystem A9000, IBM FlashSystem A9000R, and IBM XIV Storage System: Host Attachment and Interoperability, SG24-8368.
Alternatively, as previously mentioned, a volume can be mapped from the Hub view by clicking the mapping circle, as shown in Figure 2-49, which will open the same mapping view starting in Figure 2-47 on page 59.
Figure 2-49 Volume mapping in Hub view
Consistency groups
IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software enable a higher level of volume management by grouping volumes and snapshots into sets that are called consistency groups. This grouping is useful for cluster-specific volumes.
Figure 2-50 on page 61 shows the volume’s Actions menu for consistency groups. It includes the following options:
•Move a volume to a consistency group
•Remove a volume from a consistency group
The Remove from Group option is available if the volume belongs to a consistency group.
Figure 2-50 Consistency group options for a volume
Consistency groups are covered in detail in 2.5, “Consistency groups” on page 81.
Quality of service
The quality of service (QoS) feature is managed through the definition of performance classes and then the association of a volume with a performance class. To associate a volume with a performance class, select QoS on the volume’s Actions menu as shown in Figure 2-51.
Figure 2-51 Associate a volume with a performance class
Then, the storage administrator optionally can assign an existing performance class to the volume or create a performance class to associate with the volume. To create a performance class, click Create QoS performance class as shown in Figure 2-52.
Figure 2-52 Create a performance class
After this option is selected, a new tab opens so that you can create the performance class as shown in Figure 2-53 on page 62.
Figure 2-53 Creating a performance class
In this example, we opted to limit the IOPS to 100. An option also exists to make the performance class shared or independent. For a shared performance class, all of the members that are assigned to this class share the 100 IOPS. If the independent option is selected, each member that is associated with this class is limited to 100 IOPS.
After the performance class is created, you can return to the Volume tab, as shown in Figure 2-54, to associate the new class to the volume. The performance class association can be canceled at any time. All changes that relate to QoS are immediate.
Figure 2-54 Volume tab that is pending QoS application
 
Important: If more than one object (volume, host, domain, or pool) is associated with a performance class, all of those objects either share the limitation that is defined in that performance (when shared is selected) or each object is limited by the performance class (when independent is selected).
As with most of the options in the Actions menu, you can get to the same view by selecting the QoS circle in the Hub as shown in Figure 2-55.
Figure 2-55 Select QoS option from the Hub view
For more information about QoS, see IBM FlashSystem A9000 and IBM FlashSystem A9000R Architecture and Implementation, SG24-8345.
The Hyper-Scale Manager gives the storage administrator the option to view statistics from the volume’s Actions menu as shown in Figure 2-56. With this option, the storage administrator can view the performance and capacity statistics of a volume.
Figure 2-56 Viewing volume statistics
Additionally, at the bottom of the tabular view for the volumes, the statistics for a selected volume or volumes are visible. An example is shown in Figure 2-57.
Figure 2-57 Volume Statistics view
This view can be expanded to show up to two or three graphs (depending on the size of your browser window) at a time as shown in Figure 2-58 by clicking the up arrow in one of the blocks to expand the IOPS (total), latency (avg), or bandwidth (avg) in Figure 2-57. This can be either current data or historical data. Any of the graphs can be closed by clicking the x in the upper-right corner of the graph.
Figure 2-58 Volume statistics
 
Note: All statistics views can show current and historical data.
Migration
Under the Migration option of the Actions menu, the storage administrator can set up a migration from another system to this volume. This method is a secondary path to set up migration. Before you use this path, you must first establish a connection to the source system (where the data to migrate is located).
Other options that are available under this action include changing the activation state (such as activate or pause), testing the connection, and disconnecting the migration. These options are shown in Figure 2-59.
Figure 2-59 Migrate to a volume
For more information about migration, see IBM FlashSystem A9000 and A9000R Business Continuity Solutions, REDP-5401.
Online volume mobility
You can move a volume to another system with Online Volume Mobility feature. This feature is only available for IBM FlashSystem A9000 as well as between XIV Gen 3 systems and IBM Spectrum Accelerate. The Online Volume Mobility feature is described in detail in IBM FlashSystem A9000 and A9000R Business Continuity Solutions, REDP-5401.
Figure 2-60 Online Volume Mobility actions
For more information about Online Volume Mobility, see IBM FlashSystem A9000 and A9000R Business Continuity Solutions, REDP-5401.
Volume data
You can use the Volume Data action to format or copy a volume. These menu options are shown in Figure 2-61.
Figure 2-61 Volume data actions
Formatting a volume destroys all of the data that existed on the volume. A formatted volume returns zeros as a response to any read command. The volume is formatted logically, and no data is written to the physical storage space that is allocated for that volume.
A volume copy differs from a snapshot because a volume copy does not create a point-in-time copy as a child device of the original volume. The volume copy command copies all of the data in a volume at the time that the command is issued into a separate and empty volume, which is independent of the source volume.
The advantage of a volume copy over a snapshot is that a volume copy is independent, it is not at risk of automatic deletion if pool space becomes constrained. Therefore a volume copy target can also be in a different pool than the source volume.
To copy a volume, select the volume, then select Actions → Volume Data → Copy This Volume. This action opens the Copy Volume view. Complete the necessary steps by specifying the destination pool and the volume within that pool. If the volume does not exit, you optionally can create a volume, as shown in Figure 2-62.
Figure 2-62 Copy a volume
Compression
This option is available for IBM XIV Gen3. It is not available for other systems as well as volumes that are not in a thin pool. The options here include compressing a volume that meets the criteria, decompressing a compressed volume or canceling the action. An example of the options available for a compressed volume is shown in Figure 2-63.
Figure 2-63 Compression actions
Delete
The last item in the list under the Actions menu offers you the option to delete the selected volume or volumes. The GUI prompts for confirmation before the selected volumes are deleted.
Deleting a volume also deletes all of the associated snapshots, even snapshots that are part of a snapshot group. A volume can be deleted even if the volume is in the lock state. A volume that is mapped to a host or part of a consistency group cannot be deleted.
 
Important: After a volume or a snapshot is deleted, all of the data that was stored on the volume is lost, and the data cannot be restored.
2.3.3 Managing volumes with the command-line interface
All of the actions that can be performed on volumes in the GUI can also be run with the CLI. To get a list of the commands that relate to volumes, issue the following command in the CLI session:
help category=volume
This help command displays all of the commands that relate to volumes that are available in the CLI with a description of the command. Entering a command in a CLI session and then pressing the Tab key displays either the next character or a list of possible commands that start with the same letters. For example, if you entered vol_ and then pressed the Tab key, the information that is shown in Example 2-8 is displayed.
Example 2-8 List of commands that start with vol_
ITSO_2_A9000R>>vol_
vol_allocation_bitmap vol_bind_list vol_clear_external_id
vol_copy vol_create vol_create_many
vol_delete vol_diff vol_diff_copy
vol_format vol_list vol_list_extended
vol_lock vol_mapping_list vol_move
vol_rename vol_resize vol_set_external_id
vol_unlock
The use of the Tab key in this way can help you use the correct syntax and options within a command, too. See Example 2-9.
Example 2-9 Parameter list for the command vol_list
ITSO_2_A9000R>>vol_list
vol= pool= cg= show_proxy= managed= domain=
wwn=
The CLI gives you the ability to list all volumes without any of the options or list a subset of volumes, including the associated snapshots, by using an option, such as pool, as shown in Example 2-10.
Example 2-10 List all of the volumes in a pool
ITSO_2_A9000R>>vol_list pool=itso_pool1
Name Size (GB) Master Name Consistency Group Pool Creator
itso_vol1_001 20 itso_cg1 itso_pool1 admin
itso_vol1_002 20 itso_cg1 itso_pool1 admin
itso_vol2_copy 20 itso_pool1 admin
itso_vol6 40 itso_pool1 admin
itso_vol7 40 itso_pool1 admin
itso_vol3 150 itso_pool1 admin
itso_vol4 150 itso_pool1 admin
itso_vol5 150 itso_pool1 admin
itso_vol1_001.snapshot_00003 20 itso_vol1_001 itso_pool1 admin
itso_vol1_002.snapshot_00002 20 itso_vol1_002 itso_pool1 admin
To format an existing volume to remove all data and reuse the volume, run the following command:
vol_format vol=itso_vol6
All of the data on the volume is lost and unrecoverable. To bypass the warning message, use -y after the vol_format command.
Resizing a volume by using the CLI is supported only for increasing the size of the volume. To increase the size of a volume, run the following command:
vol_resize vol=itso_vol_001 size=500
The system automatically increases the size of the volume over the requested size to the nearest 103 GB boundary if the volume is within 5% of that number. The system rounds up to only that number. In our example, the resulting size of the volume, by using the command that is shown in Example 2-11, is 516 GB.
Example 2-11 Increasing the size of a volume
ITSO_2_A9000R>>vol_resize vol=itso_vol1_001 size=500
Warning: Are you sure you want to increase volume size? y/n: y
Command run successfully.
You can then list the volume to see its new size by issuing the following command:
vol_list vol=itso_vol1_001
Shrinking a volume is supported in the GUI (and used with caution). Shrinking a volume is not supported in the CLI. If the resize command is issued to shrink a volume, the CLI command fails with a CAN_NOT_SHRINK_VOLUME error message.
To move a volume from one pool to another pool to either clear space or consolidate similar volumes in a single pool, issue the vol_move command as shown:
vol_move vol=itso_vol7 pool=itso_pool2
This volume move is a simple task because the pools are only logical containers for volumes and capacity. The pointer to the volume is moved from one pool to another pool without affecting the location of the data.
Volumes can also be renamed without affecting the host I/O. To rename an existing volume, issue the following command:
vol_rename new_name=“vol_new_name” vol=“vol_old_name”
To delete an existing volume, issue the following command:
vol_delete vol=“vol_to_delete”
2.4 Snapshots
A snapshot is a point-in-time copy of a volume’s data.
The snapshot of IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software uses several innovative technologies to ensure minimal impact on system performance. Snapshots are space-efficient (redirect on write), use pointers, and contain only partitions with data that changed from the original volume. If a partition did not change, both the snapshot and the volume point to the same partition.
Because the source volume and the snapshot volume differ over time, snapshots require capacity. Space for snapshots must be set aside when you define a storage pool. The snapshot reserve space requires a minimum of 400 GB in IBM FlashSystem A9000 and A9000R, and 17 GB in IBM XIV Gen3 and IBM Spectrum Accelerate software.
An application can use many volumes on IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software. For example, a database application can span several volumes for application data and transaction logs. In this case, the snapshot for the volumes must occur at the same moment in time so that the data and logs are consistent. Creating a snapshot group of the consistency group ensures that all of the volumes that are assigned to the group are snapped at the same moment, which ensures data consistency throughout the group.
The creation and management of snapshots with IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software are straightforward. Snapshots are easy to perform. This section guides you through the lifecycle of a snapshot, providing examples of how to interact with the snapshots by using the GUI and the CLI.
2.4.1 How to create a snapshot of a volume
A snapshot of a volume or snapshots of multiple volumes can be created by using either the GUI or the CLI. To use the GUI, select the volume (or volumes) that you want. Select Actions → Snapshots → Create Snapshot(s). You can see this path in Figure 2-64.
Figure 2-64 Create a volume snapshot
The view on the right side of the GUI displays the Hub for this volume and the window to create the snapshot. If a single volume was selected, you can rename the volume. If multiple volumes were selected for snapshots, the name is generated by the system but you can change the name later.
The deletion priority can be selected now. An example of multiple snapshots with deletion priority selection is shown in Figure 2-65.
Figure 2-65 Create snapshots of multiple volumes
The new snapshots can be viewed by clicking the Sn element in the Hub, as shown in Figure 2-66.
Figure 2-66 Hub view that is expanded for snapshots
After you click the Sn circle, the GUI displays the table view with all of the snapshots and their properties, and the Hub view, as shown in Figure 2-67.
Figure 2-67 Multiple snapshots Hub view
The deletion priority in this example is set to 4 - First, but it can be changed with the drop-down list. The deletion priority is the only field that can be changed in this view.
The table view contains the specific details about each snapshot as shown in Figure 2-68. Additional columns can be displayed by moving the slider at the bottom of the window or by expanding the table view. The column views can be increased to see the entire field (such as the name of the snapshot) or decreased to see less by hovering over the name of the column to see the dividers and then by moving the divider to the wanted width. Columns can be added or removed by right-clicking the column title or by clicking the Columns icon to see the additional fields available, as shown in Figure 2-69.
Figure 2-68 Table view of snapshots
Figure 2-69 Customize columns for snapshots
From the view that is shown in Figure 2-68, you can see other details:
•The default name of the snapshot follows a specific format. The first part is the name of the volume followed by the word snapshot and then a number, or count, of snapshots for that volume. A snapshot is the same size as the volume.
•The locked property of the snapshot. By default, a snapshot is locked when it is created, which means that it is read-only.
•The modified property is displayed next to the locked field. The value changes to yes after a snapshot is unlocked.
2.4.2 Snapshot deletion priority
IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software use an automatic snapshot deletion mechanism to protect against overutilizing the snapshot space in a pool. Snapshot space overutilization can occur as new data is written to a volume, which means that the snapshot now must contain the original data from the point in time that the snapshot was taken. It can also happen as snapshots are created.
Each snapshot has a deletion priority property that is set by the user at the time of creation (and it can be modified later). Five deletion priorities from priority 4 to priority 0 (which is also known as the Golden Snapshot). Priority 0 is used to protect snapshots that must not be subject to automatic deletion and is only available on XIV and IBM Spectrum Accelerate systems and snapshot groups on FlashSystem A9000 and A9000R. The system uses this priority to determine which snapshot to delete first.
When the system needs to delete a snapshot to make room for a new snapshot (or space in the pool), it deletes the oldest snapshot with deletion priority 4. The system deletes all of the snapshots with priority 4 before it deletes snapshots with priority 3. Then, the system deletes the snapshots with priority 2. The last snapshots that are deleted by the system are the deletion priority 1 snapshots. The default deletion priority in the GUI is priority 1.
IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software provide alerts based on the percentage of the snapshot space that is used in a pool. As you receive higher-level alerts about snapshot usage, the snapshot space of the affected pool can be manually expanded to accommodate more snapshots or snapshots can be manually deleted before the automatic deletion occurs. For more information about viewing and modifying the default snapshot thresholds, see “Policy controls” on page 44.
2.4.3 Managing snapshots with the GUI
To manage snapshots from the Storage Management GUI, select Pools & Volumes Views → Snapshots. This action lists all of the snapshots on the systems in a single table view. Selecting any of the snapshots in the table enables the Actions menu.
The following actions are available:
•Properties: View and modify snapshot properties, including the lock state
•Mapping: Map snapshots, unmap snapshots, and modify snapshot mappings
•QoS: Set and cancel a performance class for a snapshot
•Statistics: View statistics for a snapshot
•Snapshot Data: Format, modify, duplicate, copy, and restore a snapshot
•Delete: Delete a snapshot
Properties
The Properties view of a snapshot also includes the ability to rename a snapshot, change the deletion priority, resize a snapshot, and change the lock state of a snapshot. These options are shown in Figure 2-70.
Figure 2-70 Snapshot properties options
Although these options are easy to run, let’s look at unlocking a snapshot. By default, a snapshot is locked when it is created, and is a read-only snapshot. By unlocking a snapshot, you can modify the data in the snapshot for testing, development, or data mining without affecting the volume.
If the data needs to be maintained in the snapshot, you can create a duplicate snapshot for the data while the original snapshot is unlocked and modified. After the modifications and testing are complete, the snapshot can be deleted, keeping the duplicate snapshot that still points to the volume. You can also copy a snapshot to perform the same activities on the copy instead of a duplicate or the original snapshot.
To unlock a snapshot, select a snapshot from the Snapshots view, then select Actions → Properties → Change Lock State to change the state as shown in Figure 2-71.
Figure 2-71 Change the lock state of a snapshot
The state of the snapshot can be toggled between unlocked or locked. The current state of the snapshot is selected. In this example, the state is locked.
To save changes that were made to a snapshot while it was unlocked, lock the snapshot by using the same process as unlocking. The locking process completes immediately, preventing further modification to the snapshot. In this case, the snapshot might no longer be a point in time copy of the source volume. A modified snapshot can be overwritten by a current point in time copy of the volume by selecting Actions → Snapshot Data → Overwrite by Volume.
 
Note: A snapshot that is unlocked and then locked again displays Yes under the Modified column in the Snapshots view. You might need to add the Modified column to the default view.
Another option is to create a duplicate or copy of the snapshot to preserve the original snapshot as a backup of the volume while the duplicate snapshot is modified after the duplicate snapshot is unlocked. The option to duplicate or copy a snapshot is under the Snapshot Data in the Actions menu.
Mapping
Mapping a snapshot is the same as mapping a volume. One difference here is that after a snapshot is mapped to a host, a locked snapshot is in a read-only state. To use the snapshot for writing, it must first be unlocked as described in the previous section.
Quality of service (QoS)
A performance class might need to be applied to an unlocked snapshot that is used for writing or even for backup operations. Select Actions → QoS, and either create a QoS definition or assign an existing performance class to the snapshot. The menu option is shown in Figure 2-72.
Figure 2-72 Setting a performance class for a snapshot
Statistics
To view the statistics that are associated with a volume, select Actions → Statistics → Show Performance Statistics as shown in Figure 2-73.
Figure 2-73 Performance statistics for a snapshot
This action opens the Statistics view under the Snapshot table view. This action is similar to the Volume Statistics view that was shown in Figure 2-58 on page 63.
Snapshot data
Other actions that you can perform on a snapshot are listed under Snapshot Data. These options include formatting a snapshot, overwriting the snapshot from the original volume, duplicating the snapshot (which is taking a snapshot of the snapshot), copying the snapshot, and restoring a volume from a snapshot. These options are shown in Figure 2-74.
Figure 2-74 Snapshot data options
Consider overwriting a snapshot. For regular backup jobs, you can decide to create snapshots, letting the system delete the old snapshots, or overwriting the existing snapshots with the latest changes to the data. For instance, a backup application requires the latest copy of the data to perform its backup operation.
The overwrite operation modified the pointers to the snapshot data to be reset to the volume. All of the pointers to the original data in the snapshot are lost, and the snapshot appears as new. Storage that was allocated for the data changes between the volume and its snapshot
is released.
To perform this operation, select Snapshot Data → Overwrite by Volume. The GUI displays the request for your confirmation, as shown in Figure 2-75. Click Apply.
Figure 2-75 Overwrite a snapshot
You can restore the data from a snapshot of a snapshot back to the original snapshot. This action can be helpful for operations where data was modified incorrectly and the data needs to be restored to the snapshot. Select Snapshot Data → Restore Snapshot. The system prompts you to select from a drop-down list the snapshot to restore from, which is useful when more than one snapshot exists to choose from.
You can restore a snapshot from its source snapshot. Select the snapshot in the Snapshot view, and then select Actions → Snapshot Data → Restore Snapshot.
Select Apply, as shown in Figure 2-76.
Figure 2-76 Restore a snapshot
After you restore a snapshot from its source snapshot, the process will modify the pointers to the snapshot so that they are now equivalent to the source snapshot pointers. This change occurs only for the partitions that are modified from the time that the source snapshot was taken. The snapshot pointer does not change and continues to point to the original data. The restore process then frees the modified partition space.
You can also restore a volume from a snapshot using a similar process from the volumes view. If a snapshot is taken and the original volume later increases in size, you can still perform the restore operation. The snapshot has the original volume size, and it will restore the original volume correctly.
Delete a snapshot
When a snapshot is no longer needed, it can easily be deleted. Select the snapshot in the Snapshots view. Then, click Actions → Delete → Delete Snapshot(s), as shown in Figure 2-77.
Figure 2-77 Deleting snapshots
The snapshots are displayed on the right side of the window. Confirm that these snapshots are the correct snapshots to delete and click Apply. An example can be seen in Figure 2-78.
Figure 2-78 Delete snapshots
 
Reminder: If a volume is deleted, all of the associated snapshots are also deleted.
2.4.4 Managing snapshots with the CLI
The CLI commands are straightforward in their functions. For a full listing of commands and usage, see IBM FlashSystem A9000R Command-Line Interface (CLI) Reference Guide, SC27-8711. The list of basic commands for a volume snapshot are displayed in Figure 2-79. Additional commands that relate to snapshots can be listed by issuing the following command:
help search=snapshot
Figure 2-79 Basic snapshot commands
To create a basic snapshot, use the snapshot_create command, as shown in Example 2-12. In this example, we specified the deletion priority. If this option is not used, the default priority is used. The other options for this command are shown:
•name
•overwrite
•ext_id
Example 2-12 Create a snapshot
ITSO_2_A9000R>>snapshot_create vol=itso_vol1_001 delete_priority=1
Command run successfully.
A snapshot can also be duplicated for testing and backups. Figure 2-80 illustrates an example of duplicating a snapshot, which is followed by listing all of the snapshots that are associated with the same volume.
Figure 2-80 Duplicate a snapshot
The CLI also allows a snapshot to be restored from another snapshot. Example 2-13 shows a more recent snapshot (00003) that is restored to a later snapshot (00002). This process results in the pointers for both snapshots that now point to the same data.
Example 2-13 Restoring a snapshot from another snapshot
ITSO_2_A9000R>>snapshot_restore snapshot=itso_vol1_001.snapshot_00003 target_snapshot=itso_vol1_001.snapshot_00002
Formatting a snapshot is also a simple process with the CLI as shown:
snapshot_format snapshot=itso_vol1_001.snapshot_00003
Unlock a snapshot by using the vol_unlock command:
vol_unlock vol=“vol_to_unlock”
Delete a snapshot by using the snapshot_delete command, as shown in Example 2-14.
Example 2-14 Deleting a snapshot
ITSO_2_A9000R>>snapshot_delete snapshot=itso_vol1_001.snapshot_00002
Command run successfully.
2.4.5 Snapshot Scheduler
The Snapshot Scheduler is an option available with Hyper-Scale Manager starting with V5.3 that allows the system administrator to automate snapshots in a pool on a defined schedule. The schedule is applied to existing and new volumes and consistency groups within the pool. The Snapshot Scheduler is available for the entire IBM Spectrum Accelerate family that is managed by the Hyper-Scale Manager.
To work with the scheduler, select a pool in the pools view. Then, under the Actions menu, select Snapshot Scheduler. The following options are available:
•View/Modify Snapshot Schedules: Allows you to make change to existing schedules.
•Add Snapshot Scheduler: Allows you to create a new schedule.
•View all the related Snapshots: Lists those snapshots that were created as a result of the scheduler.
•Volumes missing automated Snapshots
•CGs missing automated Snapshots
•Remove all Snapshot Schedules
These options are shown in Figure 2-81.
Figure 2-81 Snapshot Scheduler actions
Creating a Snapshot Schedule
This section reviews the steps that are required to create a schedule and some of the options available within adding a new schedule.
To create a schedule, select the Add Snapshot Scheduler option for the pool. You need to give the schedule a name and define what it applies to from the following options (as shown in Figure 2-82):
•Volumes & Consistency Groups
•Volumes (only Volumes not in Consistency Groups)
•Consistency Groups (only Volumes in Consistency Groups)
After you create a schedule, it affects all existing and new volumes or consistency groups that are created after the schedule is created.
Figure 2-82 Selecting a volume or consistency group
Next define the time interval (daily, varying weekly intervals for specific days, monthly, and every other month), as shown in Figure 2-83.
Figure 2-83 Selecting a time period
After selecting the time period, select the specific time for the Snapshot Scheduler to run. There can be more than one time slot for a time period. Creating an additional time to run in that time period, simply click the plus sign (+) to get a new time box, as shown in Figure 2-84.
Figure 2-84 Schedule multiple time slots
You also need to define the retention policy. This number indicates how many snapshots for the volume or consistency group that are kept on the system. The HSM displays approximately how long the snapshot will be retained. If you need snapshots to stick around for longer, creating a schedule for more snapshots to be kept might be appropriate. However, remember that the schedule applies to all volumes or consistency groups within the pool.
Figure 2-85 shows an example where snapshots created by a schedule that will be kept for approximately 2 days.
Figure 2-85 Snapshot retention definition
Figure 2-86 shows an example of creating two different types of schedules in the same pool. Notice that the schedule on the left will be taken daily for all volumes and consistency groups, and the one on the right is for volumes (not in a consistency group) and will be taken Monday through Friday.
Figure 2-86 Multiple snapshot schedules
The snapshot schedules can be modified, removed and viewed by using the Actions menu option (Figure 2-87). You can view missing snapshots for volumes and consistency groups if applicable.
Figure 2-87 Snapshot schedule actions menu
Viewing Snapshot Schedules
You can view all the pools containing snapshot schedules in all the systems managed by the Hyper-Scale Manager by selecting the Snapshot Scheduled Pools option under the Pools & Volumes Views menu as shown in Figure 2-88.
Figure 2-88 Pools with snapshot schedules
Selecting this option opens a customized filter that lists all the pools with schedules. Selecting one of the pools from the list displays the snapshot schedules in the inspector area. Figure 2-89 shows the list of pools.
Figure 2-89 List of pools with snapshot schedules
2.5 Consistency groups
A consistency group is a group of volumes of which a snapshot can be made at the same point in time. Therefore, a consistent image is made of all volumes within the group at that time. The concept of a consistency group is common among storage systems. It is necessary to perform concurrent operations collectively across a set of volumes so that the result of the operation preserves the consistency among the volumes.
For example, effective storage management activities for applications that span multiple volumes, or creating point-in-time backups, is not possible without first employing consistency groups.
This consistency among the volumes in the group is critical to maintaining data integrity from the application perspective. By first grouping the application volumes into a consistency group, it is possible to later capture a consistent state of all volumes within that group at a specified point-in-time by using a special snapshot command for consistency groups.
When you issue this type of command, the following process results:
1. Complete and destage writes across the constituent volumes.
2. Suspend I/O activity simultaneously across all volumes in the consistency group.
3. Create the snapshots.
4. Resume normal I/O activity across all volumes.
IBM XIV Gen3, IBM FlashSystem A9000 and A9000R, and IBM Spectrum Accelerate software manage these suspend and resume activities for all volumes within the consistency group.
 
Restriction: A consistency group cannot span multiple systems across IBM FlashSystem A9000 and A9000R. In IBM XIV Gen3 and IBM Spectrum Accelerate software, the concept of x-Consistency groups exists and, therefore, can have volumes from multiple systems.
2.5.1 Creating consistency groups
You can use the following methods to create a consistency group within the GUI:
•Create the consistency group and add the volumes to it.
•Choose to move a volume to a consistency group and create the consistency group then.
We first look at the second method. Under the Volumes view, select the volumes to move. The selection enables the Actions menu. Select Actions → Consistency Group → Move to a Group, as shown in Figure 2-90.
Figure 2-90 Moving volumes to a consistency group
This action opens the Volume Consistency Group wizard, as shown in Figure 2-91. The storage administrator can either select an existing consistency group or create a consistency group by clicking CREATE Consistency Group. In this example, chose to create a consistency group.
Figure 2-91 Create a consistency group from the move volumes to a group option
After the option is selected, a new screen opens that changes the view from volumes to consistency groups. The Create Consistency Group wizard is shown in Figure 2-92. Because the option to create was selected from the Volumes view, all of the fields are completed except the name of the consistency group. Also, on any of the filled-in lines (system, domain, and pool), you can optionally navigate to that object’s properties by clicking the arrow. The arrow is displayed only when the cursor is on that line.
Figure 2-92 New consistency group
This action opens a new view. You can get back to the Create Consistency Group view by closing the tab. An example of the tabs is shown in Figure 2-93. The current tab is white. The tab labeled Volume is the Volume Consistency Group tab, which is where we started. The number in red indicates the number of required fields in a tab. You can close any of the tabs to cancel the action.
Figure 2-93 Tabs that are open
After you create the consistency group, You will be returned to the volumes view. Select Apply to move the volumes to the consistency group you just created (it will now be in the list). The view now shows that the volume or volumes that you selected are in a consistency group, similar to Figure 2-94. Four volumes belong to a consistency group in the Hub display.
Figure 2-94 Hub view of volumes that belong to a consistency group
When you look at the properties of the consistency group, you can see the specific items that relate to it, including the four volumes in this example, and any associated snapshot groups and mirrors, as shown in Figure 2-95.
Figure 2-95 Hub view of a consistency group that contains volumes
Another option for creating a consistency group is to select the NEW menu and choosing Consistency Group as shown in Figure 2-96.
Figure 2-96 Create a consistency group
This action opens the Create Consistency Group window. Enter the required information for the name of the consistency group and select the system, domain, and pool, as shown in Figure 2-97.
Figure 2-97 Creating a consistency group
After all of the information is entered and applied, the consistency group is created as shown in Figure 2-98. The consistency group does not contain any volumes yet. The storage administrator can now return to the Volumes view and move volumes to this consistency group.
Figure 2-98 View the new consistency group
2.5.2 Adding volumes to a consistency group
To add volumes to a consistency group, select the volume(s) under the Volumes view and select Actions → Consistency Group → Move to a Group as shown in Figure 2-90 on page 82.
You can then select an existing consistency group from the drop-down list as shown in Figure 2-99 or create a consistency group as we did in the previous section by using the Create Consistency Group option from the list. In this example, we selected the consistency group, ITSO_RE_cg2, from the list. Click Apply (not shown), and the action is complete.
Figure 2-99 Select an existing consistency group
Now, the consistency group contains members and you can create crash consistent snapshots, either through the GUI or CLI, or by using other techniques and application programming interfaces (APIs).
2.5.3 Managing consistency groups with the GUI
As shown with other configuration tasks, the GUI makes it easy to manage consistency groups. You can set up the view in the consistency group table or continue with the default view (as described at the beginning of this chapter). To access the Consistency Groups view, select Pools & Volumes Views → Consistency Groups as shown in Figure 2-100.
Figure 2-100 Pools & Volumes Views
After the Consistency Groups option is selected, the list of consistency groups is displayed in the tabular view. To view any of the available actions on a consistency group, a consistency group must first be selected from the list.
The following actions are available:
•Properties: View and modify the properties of a consistency group.
•Pool, System: View and modify the pool that the consistency group belongs to.
•Mirror: Set up and manage a mirrored consistency group.
•HyperSwap: Set up and manage a consistency group in a HyperSwap relationship.
•Statistics: View the consistency group volume and snapshot performance and statistics.
•Members: View and modify the members of a consistency group.
•Snapshot Groups: Create and modify consistency snapshot groups.
•Delete: Delete a consistency group.
Let’s look at each option in more detail.
Properties
After a consistency group is selected from the table view, the properties of that consistency group are displayed on the right side of the browser window. Through the Properties tab, you can view and modify the name of the consistency group. This capability is indicated by the box around the editable fields. For consistency groups under properties, the editable field is the name of the group, as shown in Figure 2-101 on page 87. Editing is a simple task. Place the cursor in the field to edit the name.
Figure 2-101 Consistency group properties
Another part of the Properties view is the graphical Hub display of more details about the consistency group. Clicking any of the solid circles displays details about that object. For example, by clicking the Belonging circle, the options for viewing systems, domains, and pools are displayed as shown in Figure 2-102.
Figure 2-102 Consistency group Hub display
Clicking any of the solid circles displays the Hub details about that object. You can return to the previous window by clicking the back arrow, as shown in Figure 2-103 on page 88. Clicking the main CG circle returns the view to the properties of the consistency group. Clicking the lowest level of a circle, such as Pool, changes the table and graphical display to that object.
Figure 2-103 Use the back arrow option after you investigate an object to return to the previous view
 
Note: A circle with a dashed line indicates that no objects exist to display.
Pool and system
To view the Pool, System information that relates to a consistency group, you can also select the option from the Actions menu, as shown in Figure 2-104.
Figure 2-104 View the consistency group pool association
The Consistency Group pool and domain view in Figure 2-105 is then displayed. The storage administrator can view and move the consistency group with all its volumes and snapshots to a different domain or pool, assuming that adequate space is available. Each field has a drop-down list of the available domains and pools in the system.
Figure 2-105 Move a consistency group to another pool
Statistics
You can use the Statistics view for consistency groups to view the performance and capacity statistics for volumes and snapshots within a consistency group. To view the performance statistics, under the Consistency Groups view, select a consistency group and select either Actions → Statistics → Show Snapshots Performance Statistics or Actions → Statistics → Show Volumes Performance Statistics, as shown in Figure 2-106.
Figure 2-106 View statistics that are associated with consistency group members
Members
Members are the volumes and snapshots that make up a consistency group. The storage administrator uses this option under the consistency group Actions menu to view the volumes in a consistency group, create volumes, add or remove specific volumes, and remove all members of a consistency group, as shown in Figure 2-107.
Figure 2-107 Members of a consistency group
Snapshot groups
A consistency group, which consists of multiple volumes, allows a snapshot to be taken of all of the volumes at the same time. This action creates a synchronized snapshot of all of the volumes in the consistency group, and it is suited for applications that span multiple volumes, for example, a database application that stores its data files on multiple volumes.
After the consistency group contains volumes, snapshots can be created by selecting a consistency group in the Consistency Group view and then selecting Actions → Snapshot Groups → Create Snapshot Group, as shown in Figure 2-108. The other available options are viewing, restoring from, and deleting all snapshot groups.
Figure 2-108 Consistency group snapshot groups
After the Create Snapshot Group option is selected, you will see a window that is similar to Figure 2-109. The name of the snapshot group and the deletion priority are the only required fields. The name is prepopulated (in this case, ITSO_RE_cg.snap_group_), and can be changed. The default deletion priority is set to 1 - Last, but it can also be changed, depending on your requirements.
Figure 2-109 Create a snapshot group
 
Important: The system uses the deletion priority when the system needs to remove snapshots and snapshot groups to clear space.
After the snapshots are created, you can see the snapshots on the Snapshots view. Multiple paths exist in the GUI to perform actions on objects. For example, for snapshot groups, by selecting the snapshot group circle from the Consistency Group Properties view, you can see the Snapshot Group menu, as shown in Figure 2-110.
Figure 2-110 Snapshot group menu
 
Tip: Multiple ways to perform the same action on an object are available in the GUI.
Delete
The storage administrator can also remove a consistency group by selecting the consistency group and then by selecting Actions → Delete → Delete Consistency Group(s), as shown in Figure 2-111. Multiple consistency groups can be selected at the same time for deletion.
Figure 2-111 Delete a consistency group
Before you delete a consistency group, you must first move all of the volumes and associated snapshots out of the consistency group. If the storage administrator attempts to delete active members, the system prevents the task from completing, as shown in Figure 2-112.
Figure 2-112 Unable to delete a consistency group with members
To remove the members, select the consistency group and select Actions → Members → Remove all members.
The system prompts you for confirmation, as shown in Figure 2-113.
Figure 2-113 Remove members from a consistency group
After all of the members are removed, the consistency group can successfully be deleted.
2.5.4 Managing consistency groups with the CLI
By using the CLI session (or CLI commands), you can also perform the preceding processes. We first look at the commands that relate to consistency groups in the CLI by issuing the following command:
help category=consistency-group
The output of this command is shown in Figure 2-114.
 
Tip: Use the search command with help (help search=cg) to list the related commands.
Figure 2-114 List of consistency group commands in the CLI
To display all of the consistency groups in the system, issue the cg_list command, as shown in Example 2-15.
Example 2-15 List the consistency groups
ITSO_2_A9000R>>cg_list
Name Pool Name
itso_cg1 itso_pool1
itso_cg2 itso_pool1
itso_cg3 itso_pool2
To create a consistency group, use the cg_create command and specify the name of the consistency group with the pool name, as shown in Example 2-16.
Example 2-16 Create a consistency group with the CLI
ITSO_2_A9000R>>cg_create cg=itso_cg4 pool=itso_pool2
Command run successfully.
The next step, after you create a consistency group, is to add volumes to the group. Use the cg_vol_add command. You must specify the consistency group and the volume to add. An example is shown in Example 2-17.
Example 2-17 Add a volume to a consistency group with the CLI
ITSO_2_A9000R>>cg_add_vol cg=itso_cg4 vol=itso_vol7
Command run successfully.
The storage administrator can also remove a volume from a consistency group by using the command cg_remove_vol. In this case, only the volume must be specified. The CLI prompts for confirmation before it removes the volume from the consistency group as shown in Example 2-18.
Example 2-18 Remove a volume from a consistency group with the CLI
ITSO_2_A9000R>>cg_remove_vol vol=itso_vol7
 
Warning: Are you sure you want to remove volume 'itso_vol7' from its Consistency Group? y/n: y
Command run successfully.
Alternatively, the command can be run by using -y to avoid the prompt. This option is useful when the command is run within a script.
To create a snapshot group, issue the command as shown in Example 2-19. Additional options can be used with this command, including specifying a name for the snapshot group and the deletion priority. By issuing this command, you create all of the snapshots for all of the volumes within the group at the same time.
Example 2-19 Create a snapshot group
ITSO_2_A9000R>>cg_snapshots_create cg=itso_cg1
Command run successfully.
To get an application crash consistent snapshot group, first pause I/O from the application before you create the snapshot. Certain applications can perform this action. In the CLI, you can include commands, such as io_pause and io_resume.
You can also create a single volume snapshot of a volume within a consistency group. However, this single volume snapshot will not be consistent across all of the volumes in the consistency group.
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