Storage Pools-:
All data which is stored on the TSM server is stored in a storage pool. The technical definition of a storage pool is a collection of like media. In other words we can say it is a set of tapes or some disk space which is designated to hold specific backup data and assigned a specific set of properties. In TSM terms, a disk based storage pool stores its data on hard disk while sequential access storage pool stores its data on tape.
Primary Storage Pools and Copy Storage Pools-:
When data is sent from the client to the TSM server, it is placed in a Primary Storage Pools. As the name indicates, these pools contain the initial copies of each file that is backed up. So for any given file that is backed up, we only have one copy of that file in a primary storage pool. If that copy will damaged or will become unavailable, we would not have access to the only backup of that file.TSM provides a solution to this problem through the use of Copy Storage Pools. A Copy Storage Pool is essentially a backup of a Primary Storage Pool. It provides for redundancy of backed up data and is used to protect against loss of the media in a primary storage pool. A Copy Storage pool can be stored on-site, in the library, to protect against tape failure or can be stored off-site to be used for disaster recovery.
Migration and Storage Pool Hierarchies-:
As indicated earlier, TSM allows an administrator to establish both disk based and tape based storage pools. Since disk can be faster than tape and it allows for multiple backups to occur simultaneously, most administrators choose to do the initial backup of systems to disk based storage pools. Long term storage of backups on disk, however, can be cost prohibitive. So administrators typically use sequential access storage pools (tape) for long term storage of backups. In order to facilitate the use of multiple types of storage pools, TSM allows for an administrator to set up a Storage Pool Hierarchy. The properties of a storage pool allow an administrator to set up a percentage full beyond which a pool will not fill. When a pool reaches this percentage full, it can automatically migrate from the storage pool it’s in to another pool in the hierarchy. Typically, an administrator will set up a disk storage pool which can hold one night’s incremental backup. In the morning, the data is migrated from the disk based storage pool to the sequential access storage pool that consists of the tapes in a tape library.
Example –
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