Ancillary protocols
This chapter describes other protocols that can be used with N series systems. Being a Unified Storage solution, the N series provides more by far than CIFS, NFS, FCP, and iSCSI access. Clustered Data ONTAP solutions can scale from 1 to 24 nodes, and from the customer point of view, data backup is also crucial. Network Data Management Protocol (NDMP) is one possible backup solution.
Clustered Data ONTAP 8.2 does not currently support data access over FTP, SFTP, or HTTP.
In this chapter, we describe only an NDMP backup solution for Clustered Data ONTAP.
The following topics are covered:
12.1 Network Data Management Protocol (NDMP)
Clustered Data ONTAP provides a robust feature set, including data protection features such as Snapshot copies, intracluster asynchronous mirroring, SnapVault backups, and NDMP backups. SnapMirror is used for disaster recovery and maintains only one read-only replica of the source volume. SnapVault is used for creating read-only archival copies of your source volume. And Data ONTAP uses NDMP with third-party software for disaster recovery.
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Note: NDMP Version 3 is not supported beginning with Data ONTAP 8.2; only NDMP Version 4 is supported.
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12.1.1 About NDMP modes of operation
Starting with Data ONTAP 8.2, you can choose to perform tape backup and restore operations either at a node level as you have been doing until now or at a storage virtual machine (SVM) level. To perform these operations successfully at the SVM level, NDMP service must be enabled on the SVM.
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Note: You cannot use System Manager to enable, disable, or stop the NDMP service on storage systems running Clustered Data ONTAP 8.2. However, for storage systems running Clustered Data ONTAP 8.1 or a later version in the 8.1 release family, NDMP management is supported.
For storage systems running Data ONTAP 8.2, you should use the command-line interface to manage the NDMP service.
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In a mixed cluster where nodes are running different versions of Data ONTAP 8.2 and earlier versions in the Data ONTAP 8.x release family, NDMP follows the node-scoped behavior (at the node level). This NDMP behavior continues even after upgrading to Data ONTAP 8.2. You must explicitly disable the node-scoped NDMP mode to perform tape backup and restore operations in the SVM aware mode.
In a newly installed cluster where all nodes are running Data ONTAP 8.2, NDMP is in the SVM aware mode (at the SVM level) by default. To perform tape backup and restore operations in the node-scoped NDMP mode, you must explicitly enable the node-scoped NDMP mode.
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Note: The NDMP default password must be changed.
•In the node-scoped NDMP mode, you must use NDMP specific credentials to access a storage system in order to perform tape backup and restore operations.
•The default user ID is “root”. Before using NDMP on a node, you must change the default NDMP password associated with the NDMP user. You can also change the default NDMP user ID.
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12.1.2 Tape backup of FlexVol volumes with NDMP
Clustered Data ONTAP uses NDMP with third-party software for disaster recovery. No native tape backup or restore commands are currently available in Clustered Data ONTAP. All tape backups and restores are performed through third-party NDMP applications.
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Note: For Infinite Volumes, Data ONTAP supports tape backup and restore through a mounted volume. Infinite Volumes do not support NDMP.
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Tape backup of FlexVol volumes using NDMP
NDMP allows you to back up storage systems directly to tape, resulting in efficient use of network bandwidth. Clustered Data ONTAP supports dump engine for tape backup. Dump is a Snapshot copy-based backup to tape, in which your file system data is backed up to tape. The Data ONTAP dump engine backs up files, directories, and the applicable access control list (ACL) information to tape. You can back up an entire volume, an entire qtree, or a subtree that is neither an entire volume nor an entire qtree. Dump supports level-0, differential, and incremental backups.
You can perform a dump backup or restore by using NDMP-compliant backup applications. Starting with Data ONTAP 8.2, only NDMP Version 4 is supported.
Tape backup of Infinite Volumes using a mounted volume
You can back up and restore Infinite Volumes using any data management application that can back up files over a volume mounted with the NFS or CIFS protocols and that supports SnapDiff.
However, you cannot back up or restore Infinite Volumes with NDMP.
Tape backup and restore workflow for FlexVol volumes
The following high-level tasks are required to perform a tape backup and restore operation:
1. Set up a tape library configuration choosing an NDMP-supported tape topology.
2. Enable NDMP services on your storage system.
You can enable the NDMP services either at a node level or at an SVM level. This depends upon the NDMP mode in which you choose to perform a tape backup and restore operation.
3. Use NDMP options to manage NDMP on your storage system.
You can use NDMP options either at a node level or at an SVM level. This depends upon the NDMP mode in which you choose to perform a tape backup and restore operation.
4. Perform a tape backup or restore operation by using NDMP-enabled backup application.
Clustered Data ONTAP supports dump engine for tape backup and restore. For more information about using the backup application (also called Data Management Applications or DMAs) to perform backup or restore operations, see your backup application documentation.
A Clustered Data ONTAP system can be an ndmpcopy source or destination. The NDMP destination path is of the format /svm_name/volume_name.
Local, three-way, and remote NDMP backups
NDMP includes the following types of backups:
•Local backup: This is the simplest configuration. A backup application backs up data from an N series system to a locally attached (or SAN attached) tape device.
•Three-way backup: This configuration allows storage system data to be backed up from the storage system to another storage system that has a locally attached (or SAN attached) tape device.
•Remote NDMP backup: Like three-way backup, this configuration needs TCP/IP network and bandwidth. The data is backed up from a storage system to backup application host that has a tape divce(tape drive or tape library).
Figure 12-1 illustrates these types of backups.
Figure 12-1 Local, remote, and three-way NDMP backup
Direct Access Recovery (DAR)
Data ONTAP 8.0 or later supports enhanced DAR.
DAR is the ability of a data management application to restore a selected file of selected files without the need to sequentially read the entire tape or tapes are involved in a backup.
Enabling enhanced DAR functionality might impact the backup performance because an offset map has to be created and written onto tape. You can enable or disable enhanced DAR in both the node-scoped and SVM aware NDMP modes.
12.1.3 SVM-aware NDMP
Before introducing SVM-aware NDMP, we need to know what Cluster Aware Backup extension does.
What Cluster Aware Backup is
Cluster Aware Backup (CAB) is an NDMP Version 4 protocol extension. This extension enables the NDMP server to establish a data connection on a node that owns a volume. This also enables the backup application to determine if volumes and tape devices are located on the same node in a cluster.
To enable the NDMP server to identify the node that owns a volume and to establish a data connection on such a node, the backup application must support the CAB extension. CAB extension requires the backup application to inform the NDMP server about the volume to be backed up or restored prior to establishing the data connection. This allows the NDMP server to determine the node that hosts the volume and appropriately establish the data connection.
With the CAB extension supported by the backup application, the NDMP server provides affinity information about volumes and tape devices. Using this affinity information, the backup application can perform a local backup instead of a three-way backup if a volume and tape device are located on the same node in a cluster.
SVM-aware NDMP
Starting with Data ONTAP 8.2, you can perform tape backup and restore operations at an SVM level successfully if the NDMP service is enabled on the SVM. You can back up and restore all volumes hosted across different nodes in a cluster of an SVM if the backup application supports the CAB extension.
You can add NDMP in the allowed or disallowed protocols list by using the vserver modify command. By default, NDMP is in the allowed protocols list. If NDMP is added to the disallowed protocols list, NDMP sessions cannot be established.
An NDMP control connection can be established on different logical interface (LIF) types. In an SVM aware NDMP mode, these LIFs belong to either the data SVM or admin SVM. Data LIFs belong to the data SVM and the intercluster LIF. Node management LIFs and cluster management LIFs belong to the admin SVM.
The NDMP control connection can be established on an LIF only if the NDMP service is enabled on the SVM that owns this LIF. In an SVM context, the availability of volumes and tape devices for backup and restore operations depends upon the LIF type on which the NDMP control connection is established and the status of the CAB extension. If your backup application supports the CAB extension and a volume and tape device share the same affinity, then the backup application can perform a local backup or restore operation instead of a three-way backup or restore operation.
You can also manage NDMP on a per SVM basis by using the NDMP options and commands. In the SVM aware NDMP mode, user authentication is integrated with the role-based access control mechanism. To perform tape backup and restore operations in the node-scoped NDMP mode, you must explicitly enable the node-scoped NDMP mode.
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Note: Backups do not traverse junctions; you must list every volume to be backup up.
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12.1.4 Configuring for NDMP
Enable and configure NDMP on the node or nodes:
cdot-cluster01::> system services ndmp modify
Identify tape and library attachments:
cdot-cluster01::> system node hardware tape drive show
cdot-cluster01::> system node hardware tape library show
Configure the data management application (such as IBM Tivoli® Storage Manager) for NDMP.
12.1.5 Clustered Data ONTAP and NDMP
Clustered Data ONTAP supports the IBM Tivoli Storage Manager and Symantec NetBackup data management applications, and more are being added.
Clustered Data ONTAP supports local NDMP, remote NDMP, and three-way NDMP backup.
A data management application with DAR can restore selected files without sequentially reading entire tapes.
12.1.6 Preferred practices for disaster recovery with NDMP
Here are some ideas to consider to plan for disaster recovery with NDMP:
•Enable Snapshot copies and data-protection mirror copies for critical volumes:
– Consider putting data-protection mirror copies on SATA disks.
– Use data-protection mirror copies on SATA disks as a disk-based backup solution.
– Use intercluster data-protection mirror copies for off-site backups.
•Plan disaster-recovery implementations carefully by considering taking quorum and majority rules. (You can recover an out-of-quorum site, but doing so is not customer-friendly.)
•Use NDMP to back up important volumes to tape.
•Have a policy for rotating backups off-site for disaster recovery.
Tape backup policy during volume move, SFO, and ARL
You can continue performing incremental tape backup and restore operations after volume move, storage failover (SFO), and aggregate relocation (ARL) operations in the SVM aware NDMP mode only if your backup application supports the Cluster Aware Backup (CAB) extension.
If your backup application does not support the CAB extension or if you are using the node-scoped NDMP mode, then you can continue performing an incremental backup operation only if you migrate the LIF that is configured in the backup policy to the node that hosts the destination aggregate. Else, after volume migration, you must perform a baseline backup prior to performing the incremental backup operation.
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Note: For SFO operations, the LIF configured in the backup policy must migrate to the partner node.
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For more information about this behavior, see the Clustered Data ONTAP Data Protection Tape Backup and Recovery Guide.
Considerations when using NDMP
Keep in mind the following considerations for NDMP:
•NDMP services can generate file history data at the request of NDMP backup applications.
File history is used by backup applications to enable optimized recovery of selected subsets of data from a backup image. File history generation and processing might be time-consuming and CPU-intensive for both the storage system and the backup application.
If your data protection needs are limited to disaster recovery, where the entire backup image will be recovered, you can disable file history generation to reduce backup time. See your backup application documentation to determine if it is possible to disable NDMP file history generation.
•Firewall policy for NDMP is enabled by default on all LIF types. For information about managing firewall service and policies, see the Clustered Data ONTAP System Administration Guide for Cluster Administrators.
•In the node-scoped NDMP mode, to back up a FlexVol volume you must use the backup application to initiate a backup on a node that owns the volume. However, you cannot back up a node root volume.
•You can perform NDMP backup from any LIF as permitted by the firewall policies. If you use a data LIF, you must select one that is not configured for failover. If a data LIF fails over during an NDMP operation, the NDMP operation fails and must be re executed.
•In the node-scoped NDMP mode, NDMP data connection uses the same LIF as the NDMP control connection.
•NDMP backup path is of the format /vserver_name/volume_name/path_name, where path_name is the path of the directory, file, or Snapshot copy.
•When using ndmpcopy command for transferring data between a storage system running Data ONTAP operating in 7-Mode and a storage system running Clustered Data ONTAP:
•The ndmpcopy command must be initiated from a storage system running Data ONTAP operating in 7-Mode
•In the node-scoped mode, the destination IP address is the address of an LIF on the node on which the target volume is located
•Destination path is of the format /vserver_name/volume_name.
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Note: You should not use the ndmpcopy command for restoring a LUN between a storage system running Data ONTAP operating in 7-Mode and a storage system running Clustered Data ONTAP because the LUN is restored as a file on the destination storage system.
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For the syntax and examples of the ndmpcopy command, see the Data ONTAP Data Protection Tape Backup and Recovery Guide for 7-Mode.
•When a SnapMirror destination is backed up to tape, only the data on the volume is backed up. The SnapMirror relationships and the associated metadata are not backed up to tape. Therefore, during restore, only the data on that volume is restored and the associated SnapMirror relationships are not restored.
12.2 Further information about SAN and Fibre Channel
More details on SAN and the Fibre Channel protocol can be found in the following IBM support documents:
•Data ONTAP Data Protection Tape Backup and Recovery Guide, located at this website:
•Data ONTAP 8.2 Release notes, located at this website:
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