5.4 TSM Data Deduplication Introduction and Features

What is TSM Data Deduplication ?

TSM Data deduplication is a method of eliminating redundant data in sequential-access disk (FILE device class) primary, copy, and active-data storage pools. It retains one unique instance of the data on the storage media and replaces redundant data with a pointer to the unique data copy. The goal of deduplication is as follows
  • Reduces the amount of data that you need to store.
  • Reduces the overall amount of time that retrieving data requires. You can store more data on disk rather than on tape.
Tivoli Storage Manager v6.1 introduced server-side data deduplication. Each duplicate block of data is identified and replaced by a pointer. The pointers link to a single, retained copy after the client data is backed up and in a sequential-access storage pool that is enabled for deduplication. From Tivoli Storage Manager v6.2, included a type of data deduplication that occurs on the client side instead. 

In addition to entire files, Tivoli Storage Manager can also deduplicate parts of files that are common with parts of other files. If you update a storage pool for deduplication, Tivoli Storage Manager deduplicates the data that is already stored. No additional backup, archive, or migration is required. Client API data, from the Tivoli Storage Manager family of products, requires more overhead than backup-archive data.

TSM Deduplication Overview

Overview of data deduplication methods

Server-side deduplication
With this method, deduplication occurs after data is backed up to a storage pool that is set up for deduplication.
  • 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.
How to plan and configure TSM Server-side deduplication ?

Also Read: Difference between Server-side and Client-side Deduplication

Client-side or source-side Deduplication
With this method, the deduplication of files occurs during client backup to a deduplication-enabled storage pool.
  • Less data travels over LAN because deduplication occurs during backup.
  • Client nodes share the work with the server, identifying duplicate data.
  • Requires processing to remove duplicate data that is no longer needed.
  • Does not backup all data to the server.
  • Became available in version6.2.0.
How to plan and configure TSM Client-side deduplication ?

Restoring deduplicated files

If a user restores a file that exists in a deduplicated storage pool, the server uses the index to locate the unique chunks that were stored and reconstructs the file.

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