Strategies to minimize the use of storage space for backups

To minimize the amount of storage space that is required, Tivoli® Storage Manager backs up data by using the data deduplication and progressive incremental backup techniques.

Data deduplication

When the Tivoli Storage Manager server receives data from a client, the server identifies duplicate data extents and stores unique instances of the data extents in a directory-container storage pool. The data deduplication technique improves storage utilization and eliminates the need for a dedicated data deduplication appliance.

Figure 1. Data deduplication process
Illustration shows the data deduplication process for Tivoli Storage Manager

If the same byte pattern occurs many times, data deduplication greatly reduces the amount of data that must be stored or transferred. In addition to whole files, Tivoli Storage Manager can also deduplicate parts of files that are common with parts of other files.

Tivoli Storage Manager provides the following types of data deduplication:
Server-side data deduplication
The server identifies duplicate data extents and moves the data to a directory-container storage pool. The server-side process uses inline data deduplication, where data is deduplicated at the same time that the data is written to a directory-container storage pool. Deduplicated data can also be stored in other types of storage pools. Inline data deduplication on the server provides the following benefits:
  • Eliminates the need for reclamation
  • Reduces the space that is occupied by the stored data
Client-side data deduplication
With this method, processing is distributed between the server and the client during a backup process. The client and the server identify and remove duplicate data to save storage space on the server. In client-side data deduplication, only compressed, deduplicated data is sent to the server. The server stores the data in the compressed format that is provided by the client. Client-side data deduplication provides the following benefits:
  • Reduces the amount of data that is sent over the local area network (LAN)
  • Eliminates extra processing power and time that is required to remove duplicate data on the server
  • Improves database performance because the client-side data deduplication is also inline

You can combine both client-side and server-side data deduplication in the same production environment. The ability to deduplicate data on either the client or the server provides flexibility in terms of resource utilization, policy management, and data protection.

Compression
Use inline compression to reduce the amount of space that is stored in container storage pools. Data is compressed as it is written to the container storage pool.
Restriction: The Tivoli Storage Manager server cannot compress encrypted data.

Progressive incremental backup

In a progressive incremental backup process, the Tivoli Storage Manager server monitors client activity and backs up any files that change since the initial full backup. Entire files are backed up, so that the server does not need to reference base versions of the files. This backup technique eliminates the need for multiple full backups of client data thus saving network resources and storage space.