AIX Storage Management

system are

512, 1024 and 2048

bytes only. A compressed file system

cannot

have a fragment size of 4KB.

The choice of the fragment size for compressed file systems must be made after

evaluating the size of files to be stored and the amount of compression that is

actually achieved. Where high amounts of compression are possible, higher disk

space savings can be achieved by using a small fragment size like 512 bytes.

However, at the same time performance will degrade quite substantially.

4.2.1 Implementation of Data Compression

In AIX Version 4, data is compressed at the level of individual files logical blocks.

To compress data in large units (all the logical blocks of a file together for

example), would result in the loss of more available disk space. ...