How client (software) compression affects backup performance.

Article:TECH6052  |  Created: 2000-01-28  |  Updated: 2013-10-23  |  Article URL http://www.symantec.com/docs/TECH6052
Article Type
Technical Solution


Environment

Issue



How client (software) compression affects backup performance.

Solution



If compression is turned on at the hardware level and also at the class level, it can sometimes be a disadvantage, causing backup throughput to suffer greatly. The compression then becomes inefficient. Turning compression off at the class level, while leaving the hardware compression in place, can possibly cause the backup throughput to more than double. This, however, is not always the case.

Advantages of Compression:  
Compression reduces the size of a backup by reducing the size of files in that backup.  This, in turn, decreases the amount of media required for storage.  Because the compression and subsequent expansion is performed on the client, compression also decreases the amount of data going over the network and therefore the network load.

Disadvantages of Compression:
Compression increases computing overhead on the client and also increases backup time (due to the time required to compress the files).  In addition, the lower transfer rate associated with compression on the client reduces the ability of some tape devices (notably DLT and 8 mm) to stream data, thus causing more wear on those devices than would otherwise occur.

Nevertheless, the savings in media and network resources still make compression desirable, unless total backup time or client computing resources become a problem.  If total backup time is a problem, consider multiplexing.  The NetBackup multiplexing feature backs up clients in parallel, thus reducing the total time to back them up.

In general, it IS NOT recommended to use client (software) compression, unless backing up over a slow network link.

In general, it IS recommended to use hardware compression, unless backing up over a slow network link, AND using client (software) compression.

Client (software) compression is supported on all supported UNIX clients.


Legacy ID



199202


Article URL http://www.symantec.com/docs/TECH6052


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