Capacity planning

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Ensure that there is sufficient storage space before you install and use IBM® Storage Protect Snapshot.

The storage space that is required for IBM Storage Protect Snapshot can be divided into the following categories:

  • Space that is required for the global product installation on the system.
  • Space that is required to enable each individual database instance with IBM Storage Protect Snapshot.
  • Space that is required on the storage system to store the actual snapshot backups or clones.

Space requirement for global product installation

The space that is required for the product installation of IBM Storage Protect Snapshot varies depending on the underlying operating system. The following table shows the default installation paths and the average space requirements.

Table 1. Space requirements for a global product installation of IBM Storage Protect Snapshot
Operating system Installation path Space required (MB)
AIX® /usr/tivoli/tsfcm/acs_version_number 1250
Linux™ /opt/tivoli/tsfcm/acs_version_number 500

Space requirement for instances

IBM Storage Protect Snapshot must also be installed on each instance that is enabled for snapshot-based data protection or cloning. This process is called activation and must be started after the installation. During this process, all necessary files are copied from the installation path to an instance-specific directory. The space that is required for each IBM Storage Protect Snapshot enabled application is equal to the amount of space that is required for the global product installation.

The same amount of space is required for any backup or clone instance.

Extra space is required for IBM Storage Protect Snapshot log files. Log files are written continuously by IBM Storage Protect Snapshot without automatically deleting the older ones. You must monitor periodically the amount of space that is used by these log files and manually delete them if required.

Space requirement for snapshot copies

The snapshot copies of your application data require the most space. The space that is required depends on the following factors:

  • The total size of all volumes in the storage system that are part of the volume groups that contain the application data.
  • The type of snapshot whether it is a full copy or a space-efficient snapshot.
  • The number of backup copies.
  • The number of changes that occur on the source volumes after a snapshot is taken. This factor applies to space-efficient snapshots only.
  • In an IBM DB2® pureScale® environment where the data to be protected is on a GPFS™ file system, ensure that there is sufficient free space to store all snapshots. The size of a snapshot depends on the number of changes to the GPFS file system content that occur after the snapshot was taken. As a consequence, space requirements for a single snapshot can increase over time.
For remote mirroring with any of the following storage systems, each backup copy uses space on the remote site storage and on the local site until it is deleted.
  • XIV®
  • SAN Volume Controller
  • IBM Storwize® family

Use the MAX_VERSIONS parameter in the IBM Storage Protect Snapshot profile to limit the number of snapshots that are stored on a storage system.

On SAN Volume Controller, IBM Storwize family, and IBM System Storage® DS8000®, full snapshot copies require the same amount of space as the corresponding source volumes. If there is not enough storage space available, you can increase the capacity on the requested storage pool, or free up some items that are using existing capacity.

Volume group snapshots are supported on IBM SAN Volume Controller and IBM Storwize family.