Description

vxcompress is a new utility introduced in 6.0 to compress files on VXFs filesystem.

For now, it is only supported on Linux and Solaris. Support for HP-UX and AIX will come later.

We can compress the files on vxfs filesystem using vxcompress.

Compressed file is a file with compressed extents.

Compression can only be done on disk layout version 9.

# fstyp -v /dev/vx/rdsk/aarifdg/aarif | grep version
magic a501fcf5  version 9  ctime Fri Jan 20 06:55:41 2012

If the filesystem is lower then version 9, it will fail with error cannot use vxcompress..

To compress a file:

#vxcompress lib

To compress all the files in a directory:

#vxcompress -r dirname

Compressed file is indistinguishable from uncompressed file.

- It has the same name and same inode number

-Can be read or written as usual

-Reads cause uncompression in memory and not on disk

-Writes cause uncompression on disk

-vxcompress uses gzip to compress the file.

-Default compression strength is 6. Can specify compression strength from 1 - 9.

-Default compression block size is 1MB.

How to check if a file is compressed or not

#vxcompress -L lib

%Comp   Physical    Logical  %Exts  Alg-Str  BSize  Filename
  49%      37 KB      73 KB   100%   gzip-6  1024k  lib/cpp
  44%      31 KB      55 KB   100%   gzip-6  1024k  lib/librpcsvc.so.1
  44%      28 KB      50 KB   100%   gzip-6  1024k  lib/librt.so.1
  51%      31 KB      63 KB   100%   gzip-6  1024k  lib/libtsol.so.2
  64%       5 KB      14 KB   100%   gzip-6  1024k  lib/libsendfile.so.1

Total:    237 files       13.25 MB (55%) storage savings
bash-3.00#

-----------------------------------------------------------------------------

#fsadm -S compressed /data1
Can be used to check compression on entire filesystem

To uncompress use

#vxcompress -u