Storage pool types in TSM Server

IBM Tivoli Storage Manager supports 3 types of Storage pools. They are Primary Storage Pools, Copy Storage Pools and Active-Data Storage Pools. In this post we will see the uses of each storage pool and an example on how to define them.  Starting from TSM V7.1, we have extra storagepools added - Cloud Container and Directory Container Storagepools.

A storage pool is a collection of storage volumes. A storage volume is the basic unit of storage, such as allocated space on a disk or a single tape cartridge. The server uses the storage volumes to store backed-up, archived, or space-managed files.

Different Types of Storage Pools in TSM:

The server provides three types of storage pools that serve different purposes primary storage pools, copy storage pools, and active-data pools. You can arrange primary storage pools in a storage hierarchy. The group of storage pools that you set up for the Tivoli Storage Manager server to use is called server storage.

Also Read: TSM Storage Pool Concepts (V7 Revised)

Primary Storage Pools:

When a user tries to restore, retrieve, recall, or export file data, the requested file is obtained from a primary storage pool, if possible. Primary storage pool volumes are always located on-site. A primary storage pool can use random-access storage (DISK device class) or sequential-access storage (for example, tape or FILE device classes). TSM storage hierarchy can be configured in only group of primary pools. You can define a disk pool & tape pool and make diskpool's next destination as tape pool. This way the client backup first goes to disk pool which will be faster and then migrate it to tape later.

The server has three default, random-access (DISK) primary storage pools:

ARCHIVEPOOL
In default STANDARD policy, the destination for files that are archived from client nodes

BACKUPPOOL
In default STANDARD policy, the destination for files that are backed up from client nodes

SPACEMGPOOL
For space-managed files that are migrated from Tivoli Storage Manager for Space Management client nodes (HSM clients).

To prevent a single point of failure, create separate storage pools for backed-up and space-managed files. This also includes not sharing a storage pool in either storage pool hierarchy. Consider setting up a separate, random-access disk storage pool to give clients fast access to their space-managed files.

Syntax:   define stgpool <stgpoolname> <devclassname> pooltype=primary

Ex:       define stgpool backuppool DISK hi=90 lo=40 pooltype=primary next=tapepool
             define stgpool filepool FILE 
             define stgpool tapepool LTO pooltype=primary

If you dont give the pooltype parameter it will automatically become primary pool because default pooltype is PRIMARY

Copy Storage Pools:

Copy storage pools contain active and inactive versions of data that is backed up from primary storage pools. Copy storage pools provide a means of recovering from disasters or media failures.

Also Read: Restoring damaged Storagepool volumes

For example, when a client attempts to retrieve a file and the server detects an error in the file copy in the primary storage pool, the server marks the file as damaged. At the next attempt to access the file, the server can obtain the file from a copy storage pool.

You can move copy storage pool volumes off-site and still have the server track the volumes. Moving copy storage pool volumes off-site provides a means of recovering from an on-site disaster. A copy storage pool can use only sequential-access storage (for example, a tape device class or FILE device class).

Syntax: define stgpool <copypoolname> <devclassname> pooltype=copy maxscr=100

Ex:        define stgpool copypool LTO pooltype=copy maxscr=100
              define stgpool DRMpool LTO pooltype=copy maxscr=100

Active-Data Pools:

An active-data pool contains only active versions of client backup data. active-data pools are useful for fast client restores, reducing the number of on-site or off-site storage volumes, or reducing bandwidth when copying or restoring files that are vaulted electronically in a remote location.

Data migrated by hierarchical storage management (HSM) clients and archive data are not permitted in active-data pools. As updated versions of backup data, continue to be stored in active-data pools, older versions are deactivated and removed during reclamation processing.

Also Read: Monitoring and Managing Tape Volumes

Restoring a primary storage pool from an active-data pool might cause some or all inactive files to be deleted from the database if the server determines that an inactive file needs to be replaced but cannot find it in the active-data pool. As a best practice and to protect your inactive data, therefore, you should create a minimum of two storage pools: one active-data pool, which contains only active data, and one copy storage pool, which contains both active and inactive data. You can use the active-data pool volumes to restore critical client node data, and  afterward you can restore the primary storage pools from the copy storage pool volumes. active-data pools should not be considered for recovery of a primary pool or volume unless the loss of inactive data is acceptable.

Active-data pools can use any type of sequential-access storage (for example, a tape device class or FILE device class). However, the precise benefits of an active-data pool depend on the specific device type associated with the pool. For example, active-data pools associated with a FILE device class are ideal for fast client restores because FILE volumes do not have to be physically mounted and because the server does not have to position past inactive files that do not have to be restored. In addition, client sessions restoring from FILE volumes in an active-data pool can access the volumes concurrently, which also improves restore
performance.

Active-data pools that use removable media, such as tape or optical, offer similar benefits. Although tapes need to be mounted, the server does not have to position past inactive files. However, the primary benefit of using removable media in active-data pools is the reduction of the number of volumes used for on-site and off-site storage. If you vault data electronically to a remote location, an active-data pool associated with a SERVER device class lets you save bandwidth by copying and restoring only active data.

Syntax: define stgpool <stgpoolname> <devclassname> pooltype=activedata

Ex:  define stgpool activedatapool FILE pooltype=activedata

The server will not attempt to retrieve client files from an active-data pool during a point-in-time restore. Point-in-time restores require both active and inactive file versions. Active-data pools contain only active file versions. For optimal efficiency during point-in-time restores and to avoid switching between active-data pools and primary or copy storage pools, the server retrieves both active and inactive versions from the same storage pool and volumes.

How to copy active versions of client backup data to active-data pools

Copying active versions of client data can be done in two ways, one way you can either configure simultaneously write data to activedata pools when the backp is running and the other way is by running command COPY ACTIVEDATA.  The simultaneous-write function automatically writes active backup data to active-data pools at the same time that the backup data is written to a primary storage pool.

Also Read: TSM Server Performance Tuning Parameters

You can issue the COPY ACTIVEDATA command either manually or in an administrative schedule or maintenance script. Regardless whether you use the COPY ACTIVEDATA command or the simultaneous-write function, the Tivoli Storage Manager server writes data to an active-data pool only if the data belongs to a node that is a member of a policy domain that specifies the active-data pool as the destination for active data. 

copy activedata <primarypoolname> <activedatapoolname>

or

For simultaneously writing active data You have to update domain with the ACTIVEDESTINATION parameter. All the client nodes assigned to this domain will simultaneoulsy write data to activedatapool during backup window.

Ex: update domain <domainname> activedestination=<activedatapoolname>

       update domain AIX activedestination=activedatapool