Tape Backup Data Compression: Hardware Versus Software

Asset ID:	1-71-1018242.1
Update Date:	2012-07-31
Keywords:

Solution Type Technical Instruction Sure

Solution 1018242.1 : Tape Backup Data Compression: Hardware Versus Software

Applies to:

Sun StorageTek 9840 Tape Drive - Version Not Applicable and later
Sun StorageTek 9940 Tape Drive - Version Not Applicable and later
LTO Tape Drive - Version Not Applicable and later
Sun StorageTek T10000 Tape Drive - Version Not Applicable and later
All Platforms
Checked for relevance on 19-Jan-2012.

Goal

Tape Backup Data Compression: Hardware Versus Software

Fix

Description
This document discusses tape backup data compression, and which type of
compression is more efficient.

Steps to Follow
What is data compression and how does compression work?
Data compression permits increased storage capacity by using a mathematical algorithm that reduces redundant strings of data. For tape drives, the compression algorithm is typically implemented in hardware and removes redundancy from data by encoding patterns of input characters more efficiently. The more repeat patterns in the data, the more the data can be compressed. Therefore, the amount of data compression obtained varies depending upon the characteristics of the data.

Should I use hardware compression, software compression, or both?

Use either hardware or software compression, but NOT both. Using both will actually increase the size of the resulting file. The rule of thumb is: compression + compression = no_compression

Compression done with software typically degrades performance, as the software needs to compress the data before saving it to tape. It also takes longer to retrieve data as the software must then decompress it.

Compression done by hardware generally does not introduce overhead into the
writing or reading processes, as the newer compression chips are typically many times faster than the tape drives with which they work.

Therefore, when compression is available in the tape drive hardware/firmware, the compression feature of any software package should be turned off. This reduces the processing burden on your CPU. In addition, hardware based compression is typically much more effective. Again, DO NOT double compress; compressed files could be larger after compression and double compressing can even cause the tapes to hold less than their native capacity.

Product
Sun StorageTek 9840B Tape Drive
Sun StorageTek LTO Tape Drive
Sun StorageTek 9940 Tape Drive
Sun StorageTek T9840D Tape Drive
Sun StorageTek T9840 Tape Drive
Sun StorageTek T10000 Tape Drive
Sun StorageTek T9940 Tape Drive
Sun StorageTek SDLT Tape Drive
Sun StorageTek T9940B Tape Drive

Attachments

This solution has no attachment