Administrator's Guide


Storage Pools

TSM has two types of storage pools that serve different purposes: primary storage pools and copy storage pools.

Primary storage pool
When a client node backs up, archives, or migrates data, the data is stored in a primary storage pool. The primary storage pool is the pool that is identified as the destination in the management class associated with the data.

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 onsite.

A primary storage pool can use random access storage (DISK device class) or sequential access storage (for example, tape or FILE device classes).

TSM has three default, random access, 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 Space Manager client nodes (HSM clients)

TSM does not require separate storage pools for archive, backup, or space-managed files. However, you may want to have a separate storage pool for space-managed files. Clients are likely to require fast access to their space-managed files. Therefore, you may want to have those files stored in a separate storage pool that uses your fastest disk storage.

Copy storage pool
When an administrator backs up a primary storage pool, the data is stored in a copy storage pool. See Backing Up Storage Pools for details.

A copy storage pool can use only sequential access storage (for example, a tape device class or FILE device class).

The copy storage pool provides a means of recovering from disasters or media failures. 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 obtains the file from a copy storage pool.

You can move copy storage pool volumes offsite and still have TSM track the volumes. Moving copy storage pool volumes offsite provides a means of recovering from an onsite disaster.

An Example of Server Storage

Figure 16 shows one way to set up TSM server storage. In this example, the storage defined for the server includes:

Policies defined in management classes direct the server to store files from clients in the ARCHIVE, BACKUP, or HSM disk storage pools. For each of the three disk storage pools, the tape primary storage pool is next in the hierarchy. As the disk storage pools fill, the server migrates files to tape to make room for new files. Large files may go directly to tape. For more information about setting up a storage hierarchy, see The Storage Pool Hierarchy.

You can back up all four of the primary storage pools to the one copy storage pool. For more information on backing up primary storage pools, see Backing Up Storage Pools.

Figure 16. Example of Server Storage

Example of Server Storage


To set up this server storage hierarchy, do the following:

  1. Define the three disk storage pools, or use the three default storage pools that are defined when you install the server. Add volumes to the disk storage pools if you have not already done so.

    See Using Random Access Volumes on Disk Devices.

  2. Define policies that direct the server to initially store files from clients in the disk storage pools. To do this, you define or change management classes and copy groups so that they point to the storage pools as destinations. Then activate the changed policy. See Changing Policy with the Active Policy Set for details.

  3. Attach one or more tape devices, or a tape library, to your server system.

    To enable TSM to use the device, you must enter a series of commands like the following:

    define library
    define drive
    define devclass
    define stgpool
    
    See Chapter 4, Using Removable Media Devices with Tivoli Storage Manager for more information. For detailed information on defining a storage pool, see Defining or Updating Primary Storage Pools.

  4. Update the disk storage pools so that they point to the tape storage pool as the next storage pool in the hierarchy. See Example: Updating a Storage Pool Hierarchy.

  5. Define a copy storage pool. This storage pool can use the same tape device or a different tape device as the primary tape storage pool. See Defining a Copy Storage Pool

  6. Set up administrative schedules or a script to back up the disk storage pools and the tape storage pool to the copy storage pool. Send the volumes offsite for safekeeping. See Backing Up Storage Pools.

Defining or Updating Primary Storage Pools

This section provides a summary of parameters you can set and change for storage pools. The section also provides examples of how you can set up a storage pool hierarchy.

Task Required Privilege Class
Define storage pools System
Update storage pools System or unrestricted storage

When you define a primary storage pool, be prepared to provide some or all of the information that is shown in Table 16. Most of the information is optional. Some information applies only to random access storage pools or only to sequential access storage pools. Required parameters are marked.

Table 16. Information for Defining a Storage Pool

Information Explanation Applies to Random Access Applies to Sequential Access
Storage pool name

(Required)

The name of the storage pool. Yes Yes
Device class

(Required)

The name of the device class assigned for the storage pool. Yes Yes
Pool type The type of storage pool (primary or copy). The default is to define a primary storage pool. Once you define a storage pool, you cannot change whether it is a primary or a copy storage pool. Yes Yes
Maximum number of scratch volumes

(Required for sequential access)

When you specify a value greater than zero, the server dynamically acquires scratch volumes when needed, up to this maximum number.

For automated libraries, set this value equal to the physical capacity of the library. See Maintaining a Supply of Scratch Volumes in an Automated Library.

-- Yes
Access mode Defines access to volumes in the storage pool for user operations (such as backup and restore) and system operations (such as reclamation and server migration). Possible values are:

Read/Write
User and system operations can read from or write to the volumes.

Read-Only
User operations can read from the volumes, but not write. Server processes can move files within the volumes in the storage pool. However, no new writes are permitted to volumes in the storage pool from volumes outside the storage pool.

Unavailable
User operations cannot get access to volumes in the storage pool. No new writes are permitted to volumes in the storage pool from other volumes outside the storage pool. However, system processes (like reclamation) are permitted to move files within the volumes in the storage pool.
Yes Yes
Maximum file size To exclude large files from a storage pool, set a maximum file size. The maximum file size applies to the size of a physical file (a single client file or an aggregate of client files).

Do not set a maximum file size for the last storage pool in the hierarchy unless you want to exclude very large files from being stored in server storage.

Yes Yes
Name of the next storage pool Specifies the name of the next storage pool in the storage pool hierarchy, where files can be migrated or stored. See The Storage Pool Hierarchy. Yes Yes
Migration thresholds Specifies a percentage of storage pool occupancy at which the server begins migrating files to the next storage pool (high threshold) and the percentage when migration stops (low threshold). See Migration of Files in a Storage Pool Hierarchy. Yes Yes
Migration processes Specifies the number of processes that are used for migrating files from this storage pool. See Migration for Disk Storage Pools. Yes --
Migration delay Specifies whether migration of files should be delayed for a minimum number of days. See Keeping Files in a Storage Pool and How Tivoli Storage Manager Migrates Data from Sequential Access Storage Pools. Yes Yes
Continue migration process Specifies whether migration of files should continue even if files do not meet the requirement for migration delay. This setting is used only when the storage pool cannot go below the low migration threshold without moving additional files. See Keeping Files in a Storage Pool and How Tivoli Storage Manager Migrates Data from Sequential Access Storage Pools. Yes Yes
Cache Enables or disables cache. When cache is enabled, copies of files migrated by the server to the next storage pool are left on disk after the migration. In this way, a retrieval request can be satisfied quickly. See The Use of Cache on Disk Storage Pools. Yes --
Collocation With collocation enabled, the server attempts to keep all files belonging to a client node or a client file space on a minimal number of sequential access storage volumes. See Grouping Client Files: Collocation on Sequential Access Storage Pools. -- Yes
Reclamation threshold Specifies what percentage of reclaimable space can accumulate on a volume before the server initiates a space reclamation process for the volume. See Choosing a Reclamation Threshold. -- Yes
Reclamation storage pool Specifies the name of the storage pool to be used for storing data from volumes being reclaimed in this storage pool. Use for storage pools whose device class only has one drive or mount point. See Reclaiming Volumes in a Storage Pool with One Drive. -- Yes
Reuse delay period Specifies the number of days that must elapse after all of the files have been deleted from a volume, before the volume can be rewritten or returned to the scratch pool. See Delaying Reuse of Sequential Access Volumes. -- Yes
Overflow location Specifies the name of a location where volumes are stored when they are ejected from an automated library by the MOVE MEDIA command. Use for a storage pool that is associated with an automated library or an external library. See Managing a Full Library. -- Yes

Example: Defining a Storage Pool Hierarchy

For this example, suppose you have determined that an engineering department requires a separate storage hierarchy. You want the department's backed up files to go to a disk storage pool. When that pool fills, you want the files to migrate to a tape storage pool. You want the pools to have the following characteristics:

You can define the storage pools in a storage pool hierarchy from the top down or from the bottom up. Defining the hierarchy from the bottom up requires fewer steps. To define the hierarchy from the bottom up, perform the following steps:

  1. Define the storage pool named BACKTAPE with the following command:
    define stgpool backtape tape
    description='tape storage pool for engineering backups'
    maxsize=nolimit collocate=yes maxscratch=100
    

  2. Define the storage pool named ENGBACK1 with the following command:
    define stgpool engback1 disk
    description='disk storage pool for engineering backups'
    maxsize=5M nextstgpool=backtape highmig=85 lowmig=40
    

Example: Updating a Storage Pool Hierarchy

If you have already defined the storage pool at the top of the hierarchy, you can update the storage hierarchy to include a new storage pool.

For example, suppose you had already defined the ENGBACK1 disk storage pool. Now you have decided to set up a tape storage pool to which files from ENGBACK1 can migrate. Perform the following steps to define the new tape storage pool and update the hierarchy:

  1. Define the storage pool named BACKTAPE with the following command:
    define stgpool backtape tape
    description='tape storage pool for engineering backups'
    maxsize=nolimit collocate=yes maxscratch=100
    

  2. Specify that BACKTAPE is the next storage pool defined in the storage hierarchy for ENGBACK1. To update ENGBACK1, enter:
    update stgpool engback1 nextstgpool=backtape
    

Task Tips for Storage Pools

Table 17 gives some tips on how to accomplish some tasks that are related to storage pools.

Table 17. Task Tips for Storage Pools

For this goal Do this For more information
Keep the data for a client on as few volumes as possible Enable collocation for the storage pool Grouping Client Files: Collocation on Sequential Access Storage Pools
Reduce the number of volume mounts needed to back up multiple clients Disable collocation for the storage pool Grouping Client Files: Collocation on Sequential Access Storage Pools
Specify how the server reuses tapes Set a reclamation threshold for the storage pool

Optional: Identify a reclamation storage pool

Reclaiming Space in Sequential Access Storage Pools
Move data from disk to tape automatically when needed Set a migration threshold for the storage pool

Identify the next storage pool

Migration for Disk Storage Pools
Move data from disk to tape automatically based on how frequently users access the data or how long the data has been in the storage pool Set a migration threshold for the storage pool

Identify the next storage pool

Set the migration delay period

Migration for Disk Storage Pools
Back up your storage pools Define a copy storage pool

Set up a backup schedule

Defining a Copy Storage Pool

Automating a Basic Administrative Command Schedule

Have clients back up directly to a tape storage pool Define a sequential access storage pool that uses a tape device class

Change the policy that the clients use, so that the backup copy group points to the tape storage pool as the destination.

Defining or Updating Primary Storage Pools

Changing Policy with the Active Policy Set


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