Introduction to IBM SAN Volume Controller
This chapter introduces the IBM SAN Volume Controller storage subsystem range that is supported with the new Spectrum Virtualize software v8.4. It describes all of the relevant models, their key features, benefits, and technology.
The software that runs on the IBM SAN Volume Controller products is called IBM Spectrum Virtualize.
The IBM Spectrum Virtualize software is a proven offering that was available for years in IBM SAN Volume Controller family of storage solutions. It provides an ideal way to manage and protect huge volumes of data from mobile and social applications, enables rapid and flexible cloud services deployments, and delivers the performance and scalability that is needed to gain insights from the latest analytics technologies.
This chapter includes the following topics:
1.1 Benefits of using IBM Spectrum Virtualize
The storage virtualization functions of IBM Spectrum Virtualize are a powerful tool in the hands of storage administrators. However, for an organization to fully realize the benefits of storage virtualization, its implementation must be the result of a process that begins with identifying the organization’s goals. For a storage virtualization project to be a success, the organization must identify what it wants to achieve before it starts to think how to implement the solution.
Today, organizations are searching for affordable and efficient ways to store, use, protect, and manage their data. Also, a storage environment is required to have an easy to manage interface and be sufficiently flexible to support many applications, servers, and mobility requirements. Although business demands change quickly, some recurring customer concerns drive adoption of storage virtualization, including the following examples:
•Growing data center costs
•Inability of IT organizations to respond quickly to business demands
•Poor asset usage
•Poor availability and resultant unsatisfactory (for the customers) or challenging (for the providers) service levels
•Lack of skilled staff for storage administration
Storage virtualization is one of the foundations of building a flexible and reliable infrastructure solution that enables companies to better align to their technological needs. Storage virtualization enables an organization to achieve affordability and manageability by implementing storage pools across several physically separate disk systems (which might be from different vendors).
Storage can then be deployed from these pools, and migrated transparently between pools without interruption to the attached host systems and their applications. Storage virtualization provides a single set of tools for advanced functions, such as instant copy and remote mirroring solutions, which enables faster and seamless deployment of storage regardless of the underlying hardware.
Because the storage virtualization represented by IBM Spectrum Virtualize is a software-enabled function, it offers more features that are typically not available on a regular pure storage subsystem, including (but not limited to) the following features:
•Data compression
•Software and hardware encryption
•IBM Easy Tier for workload balancing
•Thin provisioning
•Mirroring and copy services
•Interface to Cloud Service Providers
Figure 1-1 shows these features.
Figure 1-1 IBM Spectrum Storage virtualization
IBM SAN Volume Controller systems that are running IBM Spectrum Virtualize software v8.4 reduce the number of separate environments that must be managed down to a single system.
After the initial configuration of the back-end storage subsystems, all of the daily storage management operations are performed by way of a single graphical user interface. At the same time, administrators gain access to the rich function set that is provided by IBM Spectrum Virtualize, even features that are natively available on the back-end storage systems.
Spectrum Virtualize also provides a robust command-line interface with access to many bash utilities, such as cut, grep, and sed. RESTful API and Ansible support for enterprise integration and automation are also available.
1.2 IBM SAN Volume Controller supported product range
Figure 1-2 shows the current and available IBM SAN Volume Controller models that are supported by Spectrum Virtualize software v8.4.
Earlier models of IBM SAN Volume Controller (2145-CG8) are not supported because of hardware restrictions, and thus not covered in this IBM Redbooks publication. IBM SAN Volume Controller 2145-DH8 is removed from the picture as it is not longer available.
Figure 1-2 IBM SAN Volume Controller current models
1.2.1 New in Spectrum Virtualize v8.4
IBM Spectrum Virtualize 8.4 provides more features and updates to the IBM Spectrum Virtualize family of products, of which IBM SAN Volume Controller is part.
Software changes in version 8.4.2
The following are the software changes in Spectrum Virtualize version 8.4.2:
•Support for:
 – Increased number of volumes on the system:
Max volumes changed from 10.000 → 15.864.
Only applies to systems which currently have 10K volumes (for example, V7000, FS7200, FS9100, FS9200, and IBM SAN Volume Controller.
 – Expanding and shrinking volumes in FlashCopy® mappings:
Volumes associated with User-Defined FlashCopy mappings can now be expanded. The basic rules for expanding such volumes are:
 • Source or Target volume can be expanded at any time.
 • For incremental FlashCopy maps the Target VDisk must be expanded before the Source volume can be expanded.
 • Source and Target must be same size when mapping is prepared or started.
 • Source can be shrunk but only to the size of the largest copying-or-stopping Target.
 • Target volume cannot be shrunk.
 – Safeguarded Copy function:
IBM FlashSystem Safeguarded Copy feature prevents point in time copies of data from being modified or deleted due to user errors, malicious destruction or ransomware attacks.
 – Multiple IP partnerships + multiple IP addresses and VLANs:
 • Enhanced Spectrum Virtualize Ethernet support with more than 1 IPv4 and 1 IPv6 address to be defined per port for use by Ethernet host attach protocols like iSCSI, iSER& NVMeF (in the future).
 • VLAN separation for individual IP address or as desired.
 • New Portset based configuration model for Ethernet/IP connectivity.
 • For iSCSI & iSERHost Attach and IP Replication. Extensible to NVMeF and Fibre Channel in future.
 • OBAC based per-tenant administration and partitioning model for multi tenant cloud environments.
 • New CLI model for Ethernet network configuration.
 – Non-disruptive system migration:
 • Nondisruptive volume migration between independent clusters. Enables nondisruptive migration between non-clustering platforms for example, IBM SAN Volume Controller → FS9200.
 • Can migrate volumes away from a cluster that is for example, reaching max limits.
 • Uses enhancements to SCSI (ALUA) path states. Migration is based upon Remote Copy (Metro Mirror) functionality.
 – Throttling on child pools:
Up to the version 8.4.2.0, creating a throttle for a child pool has been blocked. Now it is possible. As in other throttling types, an IO will obey the most restrictive throttling that applies to it, and each IO is counted against all the throttling that apply to it. Meaning, the throttling is hierarchical: An IO to a VDisk in a child pool will count against both parent pool and child pool throttle.
 – Downloading code through eSupport:
Allows the migration of the code download functionality to use the existing Call Home Using Rest API (CHURA) infrastructure, with the addition optional ability to use a HTTP proxy, to download packages from esupport.ibm.com. The main value here is the ability to download selected code bundles (including prerequisites, drive firmware or ifixes) without the need for the firewall hole to IBM Fix Central and more importantly by way of an HTTP proxy.
•RESTful API improvements.
•Improved web forwarding with remote support assistance.
•Improved HyperSwap® scalability:
 – A HyperSwap volume can now be expanded using the expand volume command when the volume copies are part of user-defined IBM FlashCopy mappings.
•Support for 32GB Cavium Fibre Channel adapter.
Version 8.4 features the following major software changes
The following are the software changes in Spectrum Virtualize version 8.4:
•Data reduction pool (DRP) improvements:
 – Data reduction child pool: Allows for more flexibility, such as multi-tenancy.
 – FlashCopy with redirect-on-write support: Uses DRP’s internal deduplication referencing capabilities to reduce overhead by creating references instead of copying the data. Redirect-on-write (RoW) is an alternative to the copy-on-write (CoW) capabilities.
 
Note: At the time of this writing, this capability might be used only for volumes with supported deduplication without mirroring relationships and within the same pool and I/O group. The mode selection (RoW/CoW) is automatic based on these conditions.
 – Comprestimator always on: Allows the systems to sample each volume at regular intervals, and provides the ability to display the compressibility of the data in the GUI and IBM Storage Insights at any time.
 – RAID Reconstruct Read: Increases reliability and availability by reducing chances of DRP going offline because of fixable array issues. It also uses RAID capabilities, and DRP asks for a specific data block reconstruction when a potential corruption is detected.
•Distributed RAID 1 (DRAID 1) support: Provides the ability to extend distributed RAID advantages to smaller pools of drives. This feature improves performance over traditional RAID 1 implementations, which allows a better use of flash technology. These distributed arrays can support as few as two drives with no rebuild area, and 3 - 16 drives with a single rebuild area.
 
Note: DRAID1 is not supported on SV1 and other IBM SAN Volume Controller platforms do not support RAIDs since they do not have internal storage.
•Expansion of mirrored vDisks (also known as volumes): Allows the vDisks capacity to be expanded or reduced online, without requiring an offline format and sync. This ability improves the availability of the volume for use because the new capacity is available immediately.
•Three-site replication with IBM HyperSwap support: Provides improved availability for data in three-site implementations. This feature expands on the Disaster Recovery (DR) capabilities that are inherent in this topology.
 
•Host attachment support with FC-NVMe in HyperSwap systems.
•DNS support for LDAP and NTP with full DNS length (that is, 256 characters).
•Updates to maximum configuration limits: Doubles FlashCopy mapping from 5,000 to 10,000 and increases HyperSwap volumes limit from 1,250 to 2,000.
•Password and login changes on the Spectrum Virtualize v8.4 GUI to meet today’s extra regulatory compliance with password and ID expiry and security enhancements.
•Support for internal proxy servers (also known as customer web proxy) by using IBM Call Home with cloud services and log upload features.
For more information about these new features, see this IBM Documentation web page.
1.2.2 Supported products
The following IBM SAN Volume Controller products are supported to run the Spectrum Virtualize software v8.4.2 software. Here, we list the IBM SAN Volume Controller series name and hardware machine type:
•2145-SV1, 2147-SV1
•2145-SA2, 2147-SA2
•2145-SV2, 2147-SV2
•2145-DH8
1.2.3 IBM SAN Volume Controller high-level features
This IBM Redbooks publication describes and focuses on the best practices and options to gain the optimum performance from the product, including the set of software-defined storage features.
It also describes data reduction techniques, including deduplication, compression, dynamic tiering, thin provisioning, snapshots, cloning, replication, data copy services, enhanced stretch cluster, Safeguarded Copy and IBM HyperSwap for high availability.
 
Note: The detailed technical explanations, and theory of operations, of these features are not covered in this publication. For more information about these areas, see the following publications:
•Implementing the IBM FlashSystem with IBM Spectrum Virtualize Version 8.4.2, SG24-8506
•Implementing the IBM SAN Volume Controller with IBM Spectrum Virtualize Version 8.4.2, SG24-8507
All IBM SAN Volume Controller products, running Spectrum Virtualize software, feature two types of enclosures: control engine enclosures and expansion enclosures:
•A control enclosure or storage engine manages your storage systems, communicates with the host, and manages interfaces.
Each control enclosure or storage engine is a standard 2U high, 19-inch rack mounted unit.
•An expansion enclosure enables you to increase the available capacity of the IBM SAN Volume Controller cluster that communicates with the control enclosure by way of a pair of
12 Gbps SAS connections. These expansion enclosures can house many flash (SSD) SAS type drives or hard disk drives (HDD), depending on which model of expansion enclosure is ordered.
The expansion enclosures generally have three types:
 – Figure 1-3 shows the large form factor (LFF) expansion enclosure, which can hold 12 3.5-inch drives and is 2U high.
Figure 1-3 2145 LFF expansion enclosure
 – Figure 1-4 shows the small form factor (SFF) expansion enclosure, which can hold 24 2.5-inch drives and is 2U high.
Figure 1-4 2145 SFF expansion enclosure
 – Figure 1-5 shows the large form factor high density (LFF HD) expansion enclosure, which can hold 92 3.5-inch drives (or 92 2.5-inch drives in carriers) and is 5U high.
Figure 1-5 2145 LFF HD expansion enclosure
The type and models of expansion enclosures that can attach to the relevant control enclosure or storage engine is model dependent and is described next.
Note: IBM SAN Volume Controller models SV2 and SA2 do not support any type of SAS expansion enclosures.
1.3 IBM SAN Volume Controller product range
Next, we discuss the various IBM SAN Volume Controller products that are supported in IBM Spectrum Virtualize software v8.4.2, with some more in-depth information about each product, its capabilities, features, and functions. Also supplied for each product range are links to more information about their configuration limits and restrictions, so that the customer can research any information or values that are needed to give optimum performance and adhere to best practices.
The IBM SAN Volume Controller is available in the following machines types. The only difference between them is the warranty period and both machines are functionally the same:
•2145 has 1-year warranty
•2147 has 3-year warranty
The 2147 also includes Enterprise Class Support (ECS), which gives more benefits the normal warranty terms.
For more information about the ECS program, see this IBM Documentation web page.
The SAN Volume Controller Machine Type 2145 storage engines can be clustered with IBM SAN Volume Controller Machine Type 2147 storage engines only if the extra IBM Support services that upgrades IBM SAN Volume Controller Machine Type 2145 to the equivalent IBM SAN Volume Controller Machine Type 2147 Support Terms and Conditions is purchased.
For more information about supported environments, devices, and configurations, see IBM System Storage Interoperation Center.
IBM SAN Volume Controller Model DH8
IBM SAN Volume Controller is a combined hardware and software storage virtualization system with a single point of control for storage resources. The IBM SAN Volume Controller includes many functions that are traditionally deployed separately in disk systems. By including these functions in a virtualization system, IBM SAN Volume Controller standardizes functions across virtualized storage for greater flexibility and potentially lower costs.
IBM SAN Volume Controller improves business application availability and delivers greater resource usage so you can get the most from your storage resources, and achieve a simpler, more scalable, cost-efficient IT infrastructure.
 
Note: The 2145 Model DH8 are now End of Marketing (EOM) since December 2016, and are no longer available to purchase from IBM. They are included in this publication for completeness because they support running the Spectrum Virtualize software v8.4. Service will end December 2022
Figure 1-6 shows the front view of the IBM SAN Volume Controller storage engine model DH8.
Figure 1-6 IBM SAN Volume Controller storage engine model DH8
The IBM SAN Volume Controller Storage Engine Model DH8 offers the following benefits:
•One or two Intel Xenon E5 v2 Series eight-core processors, each with 32 GB memory.
•16 Gb FC, 8 Gb FC, 10 Gb Ethernet, and 1 Gb Ethernet I/O ports for FC, iSCSI, and FCoE connectivity.
•Hardware-assisted compression acceleration (optional feature).
•12 Gb SAS expansion enclosure attachment for internal flash storage (optional feature).
•2U, 19-inch rack mount enclosure.
The 2145 Model DH8 includes three 1 Gb Ethernet ports standard for iSCSI connectivity. It can be configured with up to four I/O adapter features that provide up to 16 16 Gb FC ports, up to 16 8 Gb FC ports, or up to four 10 Gb Ethernet (iSCSI) ports.
For more information, see the Technical Description - Adapter Cards section of the announcement letter for supported configurations.
Compression workloads can benefit from Model DH8 configurations with two eight-core processors with 64 GB of memory (total system memory). Compression workloads can also benefit from the hardware-assisted acceleration that is offered by the addition of up to two compression accelerator cards.
IBM SAN Volume Controller Storage Engines can be clustered to help deliver greater performance, bandwidth, and scalability. An IBM SAN Volume Controller clustered system can contain up to four node pairs or I/O groups.
IBM SAN Volume Controller Storage Engine Model DH8 can also support expansion enclosures with the following models:
•The IBM 2145 SAN Volume Controller LFF Expansion Enclosure Model 12F
Holds up to 12 3.5-inch SAS drives in a 2U, 19-inch rack mount enclosure.
•The IBM 2145 SAN Volume Controller SFF Expansion Enclosure Model 24F
Holds up to 24 2.5-inch SAS internal flash (solid-state) drives in a 2U, 19-inch rack mount enclosure.
•The IBM 2145 SAN Volume Controller HD LFF Expansion Enclosure Model 92F
Holds up to 92 3.5-inch SAS internal flash (solid-state) drive capacity drives in a 5U, 19-inch rack mount enclosure.
Table 1-1 lists the IBM SAN Volume Controller storage engine model DH8 host, expansion drive capacity, and functions.
Table 1-1 IBM SAN Volume Controller DH8 host, drive capacity and functions summary
Feature/Function
Description
Host/SAS interfaces
 
•Four-port 16 Gb FC adapter card with shortwave SFP transceivers for 16 Gb FC connectivity
•Two-port 16 Gb FC adapter card with shortwave SFP transceivers for 16 Gb FC connectivity
•Four-port 8 Gb FC adapter card with shortwave SFP transceivers for 8 Gb FC connectivity
•Four-port 10 Gb Ethernet adapter card with SFP+ transceivers for 10 Gb iSCSI/FCoE connectivity
•Four-port 12 Gb SAS expansion enclosure attachment card
SAS expansion enclosures
 
•Model 12F/24F 2U 12 or 24 drives
•Model 92F 5U 92 drives
•NL-SAS disk drives: 4 TB, 6 TB, and 8 TB 7,200 rpm
•SAS disk drives:
 – 300 GB, 600 GB, and 900 GB 15,000 rpm
 – 900 GB, 1.2 TB, and 1.8 TB 10,000 rpm
•Flash (solid-state) drives:
 – 400 GB, 800 GB, 1.6 TB, 1.92 TB, 3.2 TB, 3.84 TB, 7.68 TB, and 15.36 TB
RAID levels
DRAID 5 (CLI-only) and 6, TRAID 5 and 6
Advanced features included with each system
•Virtualization of expansion and external storage
•Data migration
•Data Reduction Pools with thin provisioning
•UNMAP
•Compression and deduplication
•Metro Mirror (synchronous) and Global Mirror (asynchronous)
Other available advanced features
•Remote mirroring
•Easy Tier compression
•External virtualization
•Encryption
•IBM FlashCopy
•Safeguarded Copy
•IBM Spectrum Control
•IBM Spectrum Protect Snapshot
For more information about the V8.4.2.x configuration limits and restrictions for IBM System Storage SAN Volume Controller, see this IBM Support web page.
IBM SAN Volume Controller Model SV1
The IBM SAN Volume Controller (2145-SV1) is the hardware component of IBM SAN Volume Controller family, and is a combined hardware and software storage virtualization system. The IBM SAN Volume Controller includes many functions traditionally deployed separately in disk systems. By including these functions in a virtualization system, IBM SAN Volume Controller standardizes functions across virtualized storage for greater flexibility and potentially lower costs.
The IBM 2145 IBM SAN Volume Controller Storage Engine Model SV1 features the following specifications:
•Two Intel Xeon E5 v4 Series eight-core processors
•64 GB of memory (options for 256 GB of memory)
•2U, 19-inch rack mount enclosure.
•10 Gb iSCSI connectivity is standard (options for 16 Gb FC, 10 Gb iSCSI, and 25 Gb iSCSI connectivity)
Figure 1-7 shows the front view of the IBM SAN Volume Controller storage engine model SV1.
Figure 1-7 IBM SAN Volume Controller storage engine model SV1
IBM SAN Volume Controller Storage Engine Model SV1 can also support expansion enclosures with the following models:
•The IBM 2145 SAN Volume Controller LFF Expansion Enclosure Model 12F, which holds up to 12 3.5-inch SAS drives in a 2U, 19-inch rack mount enclosure
•The IBM 2145 SAN Volume Controller SFF Expansion Enclosure Model 24F, which holds up to 24 2.5-inch SAS internal flash (solid state) drives in a 2U, 19-inch rack mount enclosure
•The IBM 2145 SAN Volume Controller HD LFF Expansion Enclosure Model 92F, which holds up to 92 3.5-inch SAS internal flash (solid state) or HDD capacity drives in a 5U, 19-inch rack mount enclosure
Table 1-2 lists the IBM SAN Volume Controller storage engine model SV1 host, expansion drive capacity, and functions summary.
Table 1-2 IBM SAN Volume Controller model SV1 host, expansion drive capacity, and functions
Feature/Function
Description
Host/SAS interfaces
 
•Two-port 25 Gb Ethernet adapter card with SFP28 transceivers for 25 Gb iSCSI connectivity
•Four-port 16 Gb FC adapter card with shortwave SFP transceivers for 16 Gb FC connectivity
•Four-port 10 Gb Ethernet adapter card with SFP+ transceivers for 10 Gb iSCSI/FCoE connectivity
•Four-port 12 Gb SAS expansion enclosure attachment card
•16 Gb FC longwave SFP transceivers
SAS expansion enclosures
 
•Model 12F/24F 2U 12 or 24 drives
•Model 92F 5U 92 drives
•NL-SAS disk drives: 4 TB, 6 TB, and 8 TB 7,200 rpm
•SAS disk drives:
 – 300 GB, 600 GB, and 900 GB 15,000 rpm
 – 900 GB, 1.2 TB, and 1.8 TB 10,000 rpm
•Flash (solid state) drives: 400 GB, 800 GB, 1.6 TB, 1.92 TB, 3.2 TB, 3.84 TB, 7.68 TB, and 15.36 TB
RAID levels
DRAID 5 (CLI-only) and 6, TRAID 5 and 6
Advanced features included with each system
•Virtualization of expansion and external storage
•Data migration
•Data reduction pools with thin provisioning
•UNMAP
•Compression and deduplication
•Metro Mirror (synchronous) and Global Mirror (asynchronous)
Additional available advanced features
•Remote mirroring
•Easy Tier compression
•External virtualization
•Encryption
•FlashCopy
•Safeguarded Copy
•IBM Spectrum Control
•IBM Spectrum Protect Snapshot
Model SV1 storage engines can be added to IBM SAN Volume Controller clustered systems that include previous generation storage engine models. All nodes within a clustered system must use the same version of IBM SAN Volume Controller software. An IBM SAN Volume Controller clustered system can contain up to four node pairs.
For more information about the V8.4.2.x configuration limits and restrictions for IBM System Storage SAN Volume Controller, see this IBM Support web page.
IBM SAN Volume Controller Model SV2 and SA2
BM SAN Volume Controller, a combined hardware and software storage virtualization system with a single point of control for storage resources, delivers a single system to manage and provision heterogeneous storage systems. IBM SAN Volume Controller storage engines enable customers to update their storage technology without taking the system offline, which helps to lower total cost of ownership of their storage infrastructure.
The engines are available in two models:
•IBM SAN Volume Controller Entry Storage Engine Model SA2 with two Intel Cascade Lake eight-core processors running at 2.1 GHz
•IBM SAN Volume Controller Storage Engine Model SV2 with two Intel Cascade Lake 16-core processors running at 2.30 GHz
Both models include the following features:
•128 GB of base memory
•Four 10 Gb Ethernet ports standard for iSCSI connectivity and service technician use
•Support for up to three I/O adapter cards for 16 or 32 Gb Fibre Channel (FC) and 25 Gb iSCSI/ RoCE/iWARP over Ethernet connectivity
•Two integrated AC power supplies
•Integrated battery backup
 
Note: IBM SAN Volume Controller SV2 and SA2 do not support any type of SAS expansion enclosures.
Figure 1-8 shows the front view of the IBM SAN Volume Controller storage engine models SV2 and SA2. The front view of these two machine models are identical.
Figure 1-8 IBM SAN Volume Controller models SV2 and SA2
Table 1-3 lists the IBM SAN Volume Controller storage engine model SV2 and SA2 host connections and functions.
Table 1-3 IBM SAN Volume Controller model SV2 and SA2 host connections and functions summary
Feature/Function
Description
Host/SAS interfaces
 
•Four 10 Gb Ethernet ports standard for iSCSI connectivity and service technician processes.
•Three I/O adapter cards:
 – 16 or 32 Gb Fibre Channel (FC) and
 – 25 Gb iSCSI/ RoCE/iWARP over Ethernet connectivity
 – 16 Gb FC longwave SFP transceivers
Note: A minimum of one Fibre Channel or one Ethernet adapter is required.
RAID levels
Because SV2 and SA2 do not support internal storage, they cannot perform RAID.
Advanced features included with each system
•Virtualization of expansion and external storage
•Data migration
•Data reduction pools with thin provisioning
•UNMAP
•Compression and deduplication
•Metro Mirror (synchronous) and Global Mirror (asynchronous)
•Compression acceleration is built into the SA2 and SV2 hardware
Additional available advanced features
•Remote mirroring
•Easy Tier compression
•External virtualization
•Encryption
•FlashCopy
•IBM Spectrum Control
•IBM Spectrum Protect Snapshot
IBM SAN Volume Controller storage engines can be clustered to help deliver greater performance, bandwidth, scalability, and availability. An IBM SAN Volume Controller clustered system can contain up to four node pairs or I/O groups, for a total of eight nodes. These storage engines can be added to IBM SAN Volume Controller clustered systems that include previous generation storage engine models; that is, DH8 and SV1.
Hot-spare nodes
The loss of a node for unplanned reasons, such as hardware failure, or planned outages, such as upgrades, can result in loss of redundancy or degraded system performance. To reduce this possibility, a hot-spare node is kept powered on and visible on the system. The hot-spare node is a feature that can be purchased separately. For more information, contact your Business Partner or local IBM Sales representative.
A hot-spare node features active system ports, but no host I/O ports, and is not part of any I/O group. If a node fails or is upgraded, this spare node joins the system and assumes the place of the failed node, restoring redundancy. Only host connection on Fibre Channel ports that support node port virtualization (NPIV) can be used for hot-spare nodes.
The hot-spare node uses the same N_Port ID Virtualization (NPIV) worldwide port names (WWPNs) for its Fibre Channel ports as the failed node; therefore, host operations are not disrupted. The hot-spare node retains its node identifier when it was the spare.
During an upgrade, the spare node is added to the system when a node is removed. As each node in a system shuts down for the upgrade, it is replaced by the hot-spare node.
In addition, up to four hot-spare nodes can be configured to deliver even higher availability for the solution.
For more information about V8.4.2.x configuration limits and restrictions for IBM System Storage SAN Volume Controller, see this IBM Support web page.
1.4 Advanced functions for data reduction
The IBM SAN Volume Controller range can function as a feature-rich, software-defined storage layer that virtualizes and extends the functions of all managed storage. These functions include data reduction, dynamic tiering, copy services, and high-availability configurations. In this capacity, it acts as the virtualization layer between the host and other external storage systems, providing flexibility and extending functionality to the virtualized external storage capacity.
1.4.1 Data reduction pools
Data reduction pools (DRPs) represent a significant enhancement to the storage pool concept. The virtualization layer is primarily a simple layer that runs the task of lookups between virtual and physical extents.
With the introduction of data reduction technology, compression, and deduplication, it became more of a requirement to have an uncomplicated way to stay “thin”. DRPs enable you to automatically de-allocate (not to be confused with deduplicate) and reclaim the capacity of thin-provisioned volumes that contain deleted data.
1.4.2 Deduplication
Deduplication can be configured with thin-provisioned and compressed volumes in data reduction pools for added capacity savings. The deduplication process identifies unique chunks of data, or byte patterns, and stores a signature of the chunk for reference when writing new data chunks.
If the new chunk’s signature matches an existing signature, the new chunk is replaced with a small reference that points to the stored chunk. The same byte pattern can occur many times, resulting in the amount of data that must be stored being greatly reduced.
1.4.3 Thin provisioning
In a shared storage environment, thin provisioning is a method for optimizing the use of available storage. It relies on allocation of blocks of data on demand versus the traditional method of allocating all of the blocks up front.
This methodology eliminates almost all white space, which helps avoid the poor usage rates (often as low as 10%) that occur in the traditional storage allocation method. Traditionally, large pools of storage capacity are allocated to individual servers, but remain unused (not written to).
1.4.4 Thin-provisioned flash copies
Thin-provisioned IBM FlashCopy (or snapshot function in the GUI) uses disk space only when updates are made to the source or target data, and not for the entire capacity of a volume copy.
1.5 Advanced software features
The IBM SAN Volume Controller storage engine includes the following advanced software features:
•Data migration
•Copy services:
 – Metro Mirror
 – FlashCopy
 – 3-site replication
 – Safeguarded Copy
•EasyTier
•External virtualization
•IBM HyperSwap
1.5.1 Data migration
The IBM SAN Volume Controller range provides online volume migration while applications are running, which is possibly the greatest single benefit for storage virtualization. This capability enables data to be migrated on and between the underlying storage subsystems without any effect on the servers and applications.
In fact, this migration is performed without the knowledge of the servers and applications that it even occurred. The IBM SAN Volume Controller range delivers these functions in a homogeneous way on a scalable and highly available platform over any attached storage and to any attached server.
1.5.2 Copy services
Advanced copy services are a class of functionality within storage arrays and storage devices that enable various forms of block-level data duplication locally or remotely. By using advanced copy services, you can make mirror images of part or all of your data eventually between distant sites.
Copy services functions are implemented within an IBM SAN Volume Controller (FlashCopy and Image Mode Migration), or between one IBM SAN Volume Controller and another IBM SAN Volume Controller, or any other member of the IBM Spectrum Virtualize family, in the different modes:
•Metro Mirror is the IBM branded term for synchronous Remote Copy function.
•Global Mirror is the IBM branded term for the asynchronous Remote Copy function.
•Global Mirror with Change Volumes is the IBM branded term for the asynchronous Remote Copy of a locally and remotely created FlashCopy.
Remote replication can be implemented by using both Fibre Channel and Internet Protocol (IP) network methodologies.
FlashCopy
FlashCopy is the IBM branded name for point-in-time copy, which is sometimes called time-zero (T0) copy. This function makes a copy of the blocks on a source volume and can duplicate them on 1 - 256 target volumes.
Remote mirroring
The three remote mirroring modes are implemented at the volume layer within the IBM SAN Volume Controller storage engine. They are collectively referred to as Remote Copy capabilities. In general, the purpose of these functions is to maintain two copies of data.
Often, but not necessarily, the two copies are separated by distance. The Remote Copy can be maintained in one of two modes: synchronous or asynchronous, with a third asynchronous variant:
•Metro Mirror
•Global Mirror
•Global Mirror with Change Volumes
Safeguarded Copy
Safeguarded Copy function supports the ability to create cyber-resilient point-in-time copies of volumes that cannot be changed or deleted through user errors, malicious actions, or ransomware attacks. The system integrates with IBM Copy Services Manager to provide automated backup copies and data recovery.
The system also supports IBM Copy Services Manager as an external scheduling application. IBM Copy Services Manager coordinates and automates Safeguarded Copy function across multiple systems. IBM Copy Services Manager uses a Safeguarded policy to configure FlashCopy mapping and consistency groups automatically to create backup copies.
When Safeguarded backups are created, IBM Copy Services Manager uses the retention time for the Safeguarded backups that is based on the settings in the Safeguarded policy. After copies expire, the IBM Spectrum Virtualize software deletes the expired copies from the Safeguarded backup location.
Three-site replication
A three-site replication solution was made available in limited deployments for Version 8.3.1, where data is replicated from the primary site to two alternative sites, and the remaining two sites are aware of the difference between them. This solution ensures that if a disaster occurs at any one of the sites, the remaining two sites can establish a consistent_synchronized RC relationship among themselves with minimal data transfer; that is, within the expected RPO.
IBM Spectrum Virtualize V8.4 expands the three-site replication model to include HyperSwap, which improves data availability options in three-site implementations. Systems that are configured in a three-site topology feature high DR capabilities, but a disaster might take the data offline until the system can be failed over to an alternative site.
HyperSwap allows active-active configurations to maintain data availability, which eliminates the need to failover if communications are disrupted. This solution provides a more robust environment, allowing up to 100% uptime for data, and recovery options that are inherent to DR solutions.
To better assist with three-site replication solutions, IBM Spectrum Virtualize 3-Site Orchestrator coordinates data replication for DR and HA scenarios between systems.
IBM Spectrum Virtualize 3-Site Orchestrator is a command-line based application that runs on a separate Linux host. It configures and manages supported replication configurations on IBM Spectrum Virtualize products.
1.5.3 Easy Tier
Easy Tier is a performance function that automatically migrates or moves extents of a volume to or from one storage tier to another storage tier. The IBM SAN Volume Controller storage engine supports the following types of Easy Tier storage tiers:
•Storage Class Memory
This tier exists when the pool contains drives that use persistent memory technologies that improve endurance and speed of current flash storage device technologies.
•Tier 0 flash
This exists when the pool contains high performance flash drives.
•Tier 1 flash
This exists when the pool contains tier 1 flash drives. Tier 1 flash drives typically offer larger capacities, but slightly lower performance and write endurance characteristics.
•Enterprise tier
This tier exists when the pool contains enterprise-class MDisks, which are disk drives that are optimized for performance.
•Nearline tier
This tier exists when the pool contains nearline-class MDisks, which are disk drives that are optimized for capacity.
Consider the following points about Easy Tier:
•Easy Tier monitors the host volume I/O activity as extents are read, and migrates the most active extents to higher performing tiers.
•The monitoring function of Easy Tier is continual but, in general, extents are migrated over a 24-hour period. As extent activity cools, Easy Tier moves extents to slower performing tiers.
•Easy Tier creates a migration plan that organizes its activity to decide how to move extents. This plan can also be used to predict how extents will be migrated.
1.5.4 External virtualization
The IBM SAN Volume Controller range includes data virtualization technology to help insulate hosts, hypervisors, and applications from physical storage. This technology enables them to run without disruption, even when changes are made to the underlying storage infrastructure. The IBM SAN Volume Controller storage engine functions benefit all virtualized storage.
For example, Easy Tier and DRPs with compression help improve performance and increase effective capacity, where high-performance thin provisioning helps automate provisioning. These benefits can help extend the useful life of storage assets, and reduce costs. Because these functions are integrated into the IBM SAN Volume Controller storage engine, they also can operate smoothly together, which reduces management effort.
1.5.5 Enhanced stretched cluster
In a stretched system configuration, each site is defined as an independent failure domain. If one site experiences a failure, the other site can continue to operate without disruption. You must also configure a third site to host a quorum device that provides an automatic tie-break in the event of a potential link failure between the two main sites. The main site can be in the same room or across rooms in the data center, buildings on the same campus, or buildings in different cities. Different kinds of sites protect against different types of failures.
A stretched system is designed to continue operation after the loss of one failure domain however it cannot guarantee that it can operate after the failure of two failure domains. If the enhanced stretched system function is configured, you can enable a manual override for this situation. You can also use Metro Mirror or Global Mirror on a second system for extended DR with either an enhanced stretched system or a conventional stretched system. You configure and manage Metro Mirror or Global Mirror partnerships that include a stretched system in the same way as other Remote Copy relationships. The system supports SAN routing technology, which includes FCIP links, for inter-system connections that use Metro Mirror or Global Mirror.
The two partner systems cannot be in the same production site. However, they can be collocated with the storage system that provides the active quorum disk for the stretched system.
For more information about the Enhanced Stretch Cluster function, see IBM Documentation.
1.5.6 IBM HyperSwap
HyperSwap capability enables each volume to be presented by two IBM SAN Volume Controller storage engine I/O groups. The configuration tolerates combinations of node and site failures by using host multipathing drivers that are based on the one that is available for the IBM SAN Volume Controller storage engine.
The IBM SAN Volume Controller storage engine provides GUI management of the HyperSwap function.
For more information about the HyperSwap function, see IBM Documentation.
1.5.7 Licensing
The base license that is provided with the system includes the use of its basic functions. However, extra licenses can be purchased to expand the capabilities of the system. Administrators are responsible for purchasing extra licenses and configuring the systems within the license agreement, which includes configuring the settings of each licensed function on the system.
For more information about the licensing on the IBM SAN Volume Controller storage engine, see the chapter “Licensing and Features” in Implementing the IBM SAN Volume Controller with IBM Spectrum Virtualize Version 8.4.2, SG24-8507.
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