UPDATE STGPOOL (Update a container-copy storage pool)

Privilege class

To issue this command, you must have system privilege, unrestricted storage privilege, or restricted storage privilege for the storage pool to be updated.

Parameters

pool_name (Required)

Specifies the name of the storage pool to be updated.

MAXSCRatch

Specifies the maximum number of scratch volumes that the server can request for this storage pool. You can specify an integer in the range 0 - 100000000. If the server can request scratch volumes as needed, you do not have to define each volume to be used.

The value of this parameter is used to estimate the total number of volumes that are available in the storage pool and the corresponding estimated capacity for the storage pool.

DESCription

Specifies a description of the storage pool. This parameter is optional. The maximum length of the description is 255 characters. Enclose the description in quotation marks if it contains any blank characters. To remove an existing description, specify a null string ("").

ACCess

Specifies how server processes such as storage-pool protection and repair can access data in the storage pool. This parameter is optional. You can specify one of the following values:

READWrite

Specifies that the server can read and write to volumes in the storage pool.

READOnly

Specifies that the server can only read volumes in the storage pool. The server can use data in the storage pool to restore extents to directory-container storage pools. No operations that write to the container-copy storage pool are allowed.

UNAVailable

Specifies that the server cannot access data that is stored on volumes in the storage pool.

PROTECTPRocess

Specifies the maximum number of parallel processes that are used when you issue the PROTECT STGPOOL command to copy data to this pool from a directory-container storage pool. This parameter is optional. Enter a value in the range 1 - 20.

The time that is required to complete the copy operation might be decreased by using multiple, parallel processes. However, in some cases when multiple processes are running, one or more of the processes must wait to use a volume that is already in use by a different process.

When you select this value, consider the number of logical and physical drives that can be dedicated to this operation. To access a tape volume, the server uses a mount point and a drive. The number of available mount points and drives depends on the mount limit of the device class for the storage pool, and on other server and system activity.

If you use the preview option on the PROTECT STGPOOL command, only one process is used and no mount points or drives are needed.

REClaim

Specifies when a volume becomes eligible for reclamation and reuse. Specify eligibility as the percentage of a volume's space that is occupied by extents that are no longer stored in the associated directory-container storage pool. Reclamation moves any extents that are still stored in the associated directory-container storage pool from eligible volumes to other volumes. Reclamation occurs only when a PROTECT STGPOOL command stores data into this storage pool.

This parameter is optional. You can specify an integer in the range 1 - 100. The value 100 specifies that volumes in this storage pool are not reclaimed.

The server determines that the volume is a candidate for reclamation if the percentage of reclaimable space on a volume is greater than the reclamation threshold of the storage pool.

By setting the reclaim value to 50 percent or greater, data that is moved from two reclaimed volumes uses no more than the equivalent of one new volume.

Use caution when you use reclamation with container-copy storage pools that have offsite volumes. When an offsite volume becomes eligible for reclamation, in effect the server moves the extents on the volume back to the onsite location. If a disaster occurs onsite, the server can obtain extents from the offsite volume if the restored database refers to extents on the offsite volume. Therefore, for disaster recovery purposes, ensure that you schedule database backups to run after storage pool protection schedules and DRM move schedules have run, and ensure that all database backup volumes are taken offsite along with the DRM volumes.

Tip: Set different reclamation values for offsite container-copy storage pools and onsite container-copy storage pools. Because container-copy storage pools store deduplicated data, the data extents are spread across multiple tape volumes. When you choose a reclamation threshold for an offsite copy, carefully consider the number of available mount points and the number of tape volumes that you must retrieve if a disaster occurs. Setting a higher threshold means that you must retrieve more volumes than you would if your reclamation value was lower. Using a lower threshold reduces the number of mount points that are required in a disaster. The preferred method is to set the reclamation value for offsite copies to 60, and for onsite copies, in the range 90 - 100.

RECLAIMLIMit

Specifies the maximum number of volumes that the server reclaims when you issue the PROTECT STGPOOL command and specify the RECLAIM=YESLIMITED or RECLAIM=ONLYLIMITED option. This parameter is valid only for container-copy storage pools. This parameter is optional. You can specify one of the following values:

NOLimit

Specifies that all volumes in the container-copy storage pool are processed for reclamation.

vol_limit

Specifies the maximum number of volumes in the container-copy storage pool that are reclaimed. The value that you specify determines how many new scratch tapes are available after reclamation processing completes. You can specify a number in the range 1 - 100000.

REUsedelay

Specifies the number of days that must elapse after all extents are deleted from a volume before the volume can be rewritten or returned to scratch status. This parameter is optional. You can specify an integer in the range 0 - 9999. A value of 0 means that a volume can be rewritten or returned to scratch status as soon as all the extents are deleted from the volume.

Tip: Use this parameter to ensure that when you restore the database to an earlier level, database references to extents in the storage pool are still valid. You must set this parameter to a value greater than the number of days you plan to retain the oldest database backup. If you use disaster recovery manager, the number of days that are specified for this parameter must be the same as the number specified for the SET DRMDBBACKUPEXPIREDAYS command.