5.5 TSM Server-side deduplication Overview

TSM Server-side deduplication process Overview

• More data travels over LAN because it backs up data first. Server option DEDUPREQUIRESBACKUP YES

• Client does not do any of the processing to remove duplicate data.

• Backs up all data to the server.

• Became available in version 6.1.0.

• Reclamation of volumes in the primary storage pool, copy storage pool, or active-data pool.

• Backing up of a primary storage pool to a copy storage.

• Copying of active data in the primary storage pool to an active-data pool.

• Migrating data from the primary storage pool to another primary storage pool.

• Moving data from the primary storage pool to a different primary storage pool that is also set up for deduplication, moving data within the same copy storage pool, or moving data within the same active-data pool.

• Data is sent from clients to the server.

• The server creates extents and pointers to the hash index in the server database to relate files to extents.

• The Backup Stgpool operation copies data to an undeduplicated copy storage pool.

• Reclaim operations remove duplicate data extents from the primary storage pool. This operation frees unused space.

• With this approach, deduplication is performed out-of-band, and at least one copy of non-deduplicated data exists.

• Before setting up storage pools for deduplication, determine which client nodes have data that you want to deduplicate.

• Determine which client nodes use this method. You might want to have some clients use server-side and others use client-side deduplication.

• Decide whether you want to define a new storage pool exclusively for deduplication or update an existing storage pool.

• The storage pool must be a sequential-access disk (FILE) pool. Deduplication occurs at the storage pool level. All data within a storage pool, except encrypted data, is deduplicated.

• Decide how you want to control duplicate-identification processes: Automatically Manually.

• If you have a primary sequential-access disk storage pool and a copy sequential-access disk storage pool, and both pools are set up for deduplication, you might want to run duplicate-identification processes for the primary storage pool only. In this way, only the primary storage pool reads and deduplicates data.

• When the data is moved to the copy storage pool that has deduplication enabled, the deduplication is preserved. No duplicate identification is required.

• If you plan to use Simultaneous Write Migration, that data cannot go to a deduplication-enabled storage pool.

• Disables AUTOCOPY option on the storage pool. Issues warning message.

Controlling number of deduplication processes

Effects of turning deduplication off or on 

• UPDATE STGPOOL DEDUPLICATE=NO

• UPDATE STGPOOL DEDUPLICATE=YES

• New data that enters the storage pool is not deduplicated.

• Deduplicated data, stored in the storage pool before you turned deduplication off, is not reassembled.

• Deduplicated data continues to be removed because of normal reclamation and deletion. All information about deduplication for the storage pool is retained.

• Duplicate-identification processes resume.

• Files that have already been processed are skipped.

Tips for deduplication