UPDATE STGPOOL (Update an active-data sequential access)

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 active-data pool to be updated.

DESCription

Specifies a description of the active-data 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 client nodes and server processes (such as reclamation) can access files in the active-data pool. This parameter is optional. You can specify the following values:

READWrite

Specifies that files can be read from and written to the volumes in the active-data pool.

READOnly

Specifies that client nodes can read only files that are stored on the volumes in the active-data pool.

Server processes can move files within the volumes in the storage pool. The server can use files in the active-data pool to restore active versions of backup files to primary storage pools. However, no new writes are allowed to volumes in the active-data pool from volumes outside the storage pool. A storage pool cannot be copied to the active-data pool.

UNAVailable

Specifies that client nodes cannot access files that are stored on volumes in the active-data pool.

Server processes can move files within the volumes in the storage pool. The server can use files in the active-data pool to restore active versions of backup files to primary storage pools. However, no new writes are allowed to volumes in the active-data pool from volumes outside the storage pool. A storage pool cannot be copied to the active-data pool.

COLlocate

Specifies whether the server attempts to keep data, which is stored on as few volumes as possible, that belong to one of the following candidates:

• A single client node
• A group of file spaces
• A group of client nodes
• A client file space

This parameter is optional.

Collocation reduces the number of sequential access media mounts for restore, retrieve, and recall operations. However, collocation increases both the amount of server time that is needed to collocate files for storing and the number of volumes required.

You can specify one of the following options:

No

Specifies that collocation is disabled.

GRoup

Specifies that collocation is enabled at the group level for client nodes or file spaces. For collocation groups, the server attempts to put data for nodes or file spaces that belong to the same collocation group on as few volumes as possible.

If you specify COLLOCATE=GROUP but do not define any collocation groups, or if you do not add nodes or file spaces to a collocation group, data is collocated by node. Consider tape usage when you organize client nodes or file spaces into collocation groups.

For example, if a tape-based storage pool consists of data from nodes and you specify COLLOCATE=GROUP, the server completes the following actions:

• Collocates the data by group for grouped nodes. Whenever possible, the server collocates data that belongs to a group of nodes on a single tape or on as few tapes as possible. Data for a single node can also be spread across several tapes that are associated with a group.
• Collocates the data by node for ungrouped nodes. Whenever possible, the server stores the data for a single node on a single tape. All available tapes that already have data for the node are used before available space on any other tape is used.

If a tape-based storage pool consists of data from grouped file spaces and you specify COLLOCATE=GROUP, the server completes the following actions:

• Collocates by group, the data for grouped file spaces only. Whenever possible, the server collocates data that belongs to a group of file spaces on a single tape or on as few tapes as possible. Data for a single file space can also be spread across several tapes that are associated with a group.
• Collocates the data by node (for file spaces that are not explicitly defined to a file space collocation group). For example, node1 has file spaces named A, B, C, D, and E. File spaces A and B belong to a filespace collocation group but C, D, and E do not. File spaces A and B are collocated by filespace collocation group, while C, D, and E are collocated by node.

Data is collocated on the least amount of sequential access volumes.

NODe

Specifies that collocation is enabled at the client node level. For collocation groups, the server attempts to put data for one node on as few volumes as possible. If the node has multiple file spaces, the server does not try to collocate those file spaces. For compatibility with an earlier version, COLLOCATE=YES is still accepted by the server to specify collocation at the client node level.

If a storage pool contains data for a node that is a member of a collocation group and you specify COLLOCATE=NODE, the data is collocated by node.

FIlespace

Specifies that collocation is enabled at the file space level for client nodes. The server attempts to place data for one node and file space on as few volumes as possible. If a node has multiple file spaces, the server attempts to place data for different file spaces on different volumes.

REClaim

Specifies when the server reclaims a volume, which is based on the percentage of reclaimable space on a volume. Reclaimable space is the amount of space that is occupied by files that are expired or deleted from the IBM Spectrum Protect™ database.

Reclamation makes the fragmented space and space occupied by inactive backup files on volumes usable again by moving any remaining unexpired files and active backup files from one volume to another volume. This action makes the original volume available for reuse. This parameter is optional. You can specify an integer 1 - 100. The value 100 means that reclamation is not completed.

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.

If you change the value from the default of 60, specify a value of 50 percent or greater so that files stored on two volumes can be combined onto a single output volume.

When an active-data pool volume that is offsite becomes eligible for reclamation, the reclamation process attempts to obtain the active files on the reclaimable volume from a primary or active-data pool that is onsite. The process then writes these files to an available volume in the original active-data pool. Effectively, these files are moved back to the onsite location. However, the files can be obtained from the offsite volume after a disaster if a database backup is used that references the files on the offsite volume. Because of the way reclamation works with offsite volumes, use it carefully with active-data pools.

RECLAIMPRocess

Specifies the number of parallel processes to use for reclaiming the volumes in this storage pool. This parameter is optional. Enter a value 1 - 999.

When you calculate the value for this parameter, consider the following resources that are required for reclamation processing:

• The number of sequential storage pools.
• The number of logical and physical drives that can be dedicated to the operation.

To access sequential volumes, IBM Spectrum Protect uses a mount point and, if the device type is not FILE, a physical drive.

For example, suppose that you want to reclaim the volumes from two sequential storage pools simultaneously and that you want to specify four processes for each of the storage pools. The storage pools have the same device class. Each process requires two mount points and, if the device type is not FILE, two drives. (One of the drives is for the input volume, and the other drive is for the output volume.) To run eight reclamation processes simultaneously, you need a total of at least 16 mount points and 16 drives. The device class for each storage pool must have a mount limit of at least eight.

You can specify one or more reclamation processes for each active-data pool. You can specify multiple concurrent reclamation processes for a single active-data pool, which makes better use of your available tape drives or FILE volumes. If multiple concurrent processing is not necessary, specify a value of 1 for the RECLAIMPROCESS parameter.

OFFSITERECLAIMLimit

Specifies the number of offsite volumes that space is reclaimed from during reclamation for this storage pool. This parameter is optional. You can specify the following values:

NOLimit

Specifies that you want to reclaim the space in all of your offsite volumes.

number

Specifies the number of offsite volumes to reclaim space from. You can specify an integer 0 - 99999. A value of zero means that none of the offsite volumes are reclaimed.

Tip:

To determine the value for the OFFSITERECLAIMLIMIT, use the statistical information in the message that is issued at the end of the offsite volume reclamation operation. The statistical information includes the following items:

• The number of offsite volumes that were processed
• The number of parallel processes that were used
• The total amount of time required for the processing

The order in which offsite volumes are reclaimed is based on the amount of unused space in a volume. (Unused space includes both space that has never been used on the volume and space that has become empty because of file deletion.) Volumes with the largest amount of unused space are reclaimed first.

For example, suppose an active-data pool contains three volumes: VOL1, VOL2, and VOL3. VOL1 has the largest amount of unused space, and VOL3 has the least amount of unused space. Suppose further that the percentage of unused space in each of the three volumes is greater than the value of the RECLAIM parameter. If you do not specify a value for the OFFSITERECLAIMLIMIT parameter, all three volumes are reclaimed when the reclamation runs. If you specify a value of 2, only VOL1 and VOL2 are reclaimed when the reclamation runs. If you specify a value of 1, only VOL1 is reclaimed.

MAXSCRatch

Specifies the maximum number of scratch volumes that the server can request for this storage pool. This parameter is optional. You can specify an integer 0 - 100000000. By allowing the server to request scratch volumes as needed, you avoid having to define each volume to be used.

The value that is specified for this parameter is used to estimate the total number of volumes available in the active-data pool and the corresponding estimated capacity for the active-data pool.

Scratch volumes are automatically deleted from the storage pool when they become empty. However, if the access mode for a scratch volume is OFFSITE, the volume is not deleted from the active-data pool until the access mode is changed. An administrator can query the server for empty, offsite scratch volumes and return them to the onsite location.

When scratch volumes with the device type of FILE become empty and are deleted, the space that the volumes occupied is freed by the server and returned to the file system.

Tip: For server-to-server operations that use virtual volumes and that store a small amount of data, consider specifying a value for the MAXSCRATCH parameter that is higher than the value you typically specify for write operations to other types of volumes. After a write operation to a virtual volume, IBM Spectrum Protect marks the volume as FULL, even if the value of the MAXCAPACITY parameter on the device-class definition is not reached. The IBM Spectrum Protect server does not keep virtual volumes in FILLING status and does not append to them. If the value of the MAXSCRATCH parameter is too low, server-to-server operations can fail.

REUsedelay

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

Tip: Use this parameter to ensure that when you restore the database to an earlier level, database references to files in the active-data 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. The number of days that are specified for this parameter must be the same as the number specified for the SET DRMDBBACKUPEXPIREDAYS command.

OVFLOcation

Specifies the overflow location for the storage pool. The server assigns this location name to a volume that is ejected from the library by the MOVE MEDIA command. This parameter is optional. The location name can be a maximum length of 255 characters. Enclose the location name in quotation marks if the location name contains any blank characters.

To remove an existing value, specify a null string ("").

CRCData

Specifies whether a cyclic redundancy check (CRC) validates storage pool data when audit volume processing occurs on the server. This parameter is only valid for NATIVE data format storage pools. This parameter is optional. The default value is NO. By setting CRCDATA to YES and scheduling an AUDIT VOLUME command, you can continually ensure the integrity of data that is stored in your storage hierarchy. You can specify the following values:

Yes

Specifies that data is stored containing CRC information, allowing for audit volume processing to validate storage pool data. This mode impacts performance because more processing is required to calculate and compare CRC values between the storage pool and the server.

No

Specifies that data is stored without CRC information.

Tip:

For storage pools that are associated with the 3592, LTO, or ECARTRIDGE device type, logical block protection provides better protection against data corruption than CRC validation for a storage pool. If you specify CRC validation for a storage pool, data is validated only during volume auditing operations. Errors are identified after data is written to tape.

To enable logical block protection, specify a value of READWRITE for the LBPROTECT parameter on the DEFINE DEVCLASS and UPDATE DEVCLASS commands for the 3592, LTO, or ECARTRIDGE device types. Logical block protection is supported only on the following types of drives and media:

• IBM® LTO5 and later.
• IBM 3592 Generation 3 drives and later with 3592 Generation 2 media and later.
• Oracle StorageTek T10000C and T10000D drives.

DEDUPlicate

Specifies whether the data that is stored in this storage pool is deduplicated. This parameter is optional and is valid only for storage pools that are defined with a FILE-type device class.

IDENTIFYPRocess

Specifies the number of parallel processes to use for server-side data deduplication. This parameter is optional and is valid only for storage pools that are defined with a FILE device class. Enter a value 1 - 50.

Remember: Data deduplication processes can be either active or idle. Processes that are working on files are active. Processes that are waiting for files to work on are idle. Processes remain idle until volumes with data to be deduplicated become available. The output of the QUERY PROCESS command for data deduplication includes the total number of bytes and files that have been processed since the process first started. For example, if a data deduplication process processes four files, becomes idle, and then processes five more files, then the total number of files processed is nine. Processes end only when canceled or when the number of data-deduplication processes for the storage pool is changed to a value less than the number currently specified.