Administrator's Guide


Defining a Copy Storage Pool

Use a copy storage pool to back up one or more primary storage pools. See Table 16 and Backing Up Storage Pools for more information. When you define a copy storage pool, be prepared to provide some or all of the information in Table 15.

Table 15. Information for Defining a Copy Storage Pool

Information Explanation
Device class Specifies the name of the device class assigned for the storage pool. This is a required parameter.
Pool type Specifies that you want to define a copy storage pool. This is a required parameter. Updating a storage pool cannot change whether the pool is a primary or copy storage pool.
Access mode Defines access to volumes in the storage pool for user operations (such as backup and restore) and system operations (such as reclamation). 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. However, system processes can move files within the volumes in the storage pool.

Unavailable
Specifies that users cannot access files stored on volumes in the copy storage pool. Files can be moved within the volumes of the copy storage pool, but no new writes are permitted to the volumes in the storage pool from volumes outside the storage pool.
Maximum number of scratch volumes When you specify a value greater than zero, the server dynamically acquires scratch volumes when needed, up to this maximum number. This is a required parameter.
Collocation When collocation is 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 Collocation on Copy Storage Pools.
Reclamation threshold Specifies when to initiate reclamation of volumes in the copy storage pool. Reclamation is a process that moves any remaining active, fragmented files from one volume to another volume, thus making the original volume available for reuse. A volume is eligible for reclamation when the percentage of unused space on the volume is greater than the reclaim parameter value.

Reclamation processing works differently for offsite storage pool volumes and virtual volumes. When a copy storage pool volume that is offsite becomes eligible for reclamation, the reclamation process attempts to retrieve the active files on the reclaimable volume from a primary or copy storage pool volume that is onsite. The process then writes these files to an available volume in the original copy storage pool. See Reclamation for Copy Storage Pools and Reclamation of Volumes with the Device Type of SERVER for more details.

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 Reclaimed Volumes.

Example: Defining a Copy Storage Pool

Assume you need to maintain copies of the files stored in BACKUPPOOL, ARCHIVEPOOL, and SPACEMGPOOL (default disk storage pools) for disaster recovery purposes. You want to create a copy storage pool named DISASTER-RECOVERY. You decide to use only scratch tapes in the new pool, setting the maximum number of scratch volumes to an appropriate value. You enter the following command:

define stgpool disaster-recovery tapeclass pooltype=copy
maxscratch=100

To store data in the new storage pool, you must back up the primary storage pools (BACKUPPOOL, ARCHIVEPOOL, and SPACEMGPOOL) to the DISASTER-RECOVERY pool. See Backing Up Storage Pools.

Comparing Primary and Copy Storage Pools

Table 16 compares the characteristics of primary and copy storage pools.

Table 16. Comparing Primary and Copy Storage Pools

Characteristic Primary storage pool Copy storage pool
Destination for backed-up or archived files (specified in backup or archive copy groups) Yes No
Destination for space-managed files (specified in the management class) Yes No
Offsite access mode for volumes No Yes, except for volumes with device type SERVER
Destroyed access mode for volumes Yes No
Random access storage volumes Yes No
Sequential access storage volumes Yes Yes
Contents Client files (backup versions, archived files, space-managed files) Copies of files that are stored in primary storage pools
Moving data allowed Within the same primary storage pool, or to any primary storage pool Within the same pool only.

If volumes are offsite, data is copied from the original files in primary storage pools.

Collocation Yes (sequential access storage pools only) Yes
Reclamation Yes (sequential access storage pools only) Yes

Virtual volumes (volumes with device type SERVER) and offsite volumes are handled differently. For details, see Reclamation of Volumes with the Device Type of SERVER and Reclamation of Offsite Volumes.

File deletion Files are deleted:

  • During inventory expiration processing, if the files have expired

  • When a file space is deleted

  • When a volume is deleted with the option to discard the data

  • When a primary storage pool volume is audited with the FIX=YES option, if the files on the volume are damaged and no other copies of the file exist
Files are deleted:

  • Whenever the primary copy of the file is deleted from the primary storage pool (because of expiration, file space deletion, or volume deletion)

  • When a volume is deleted with the option to discard the data

  • When a copy storage pool volume is audited with the FIX=YES option, if the files on the volume are damaged


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