Compression Performance Results

"Tristan Rhodes" <tristanr-gOv+VWruyeBS6pTDpnvEHvU/[email protected]>
Newsgroups gmane.comp.sysutils.backup.dar.general
Message-ID <[email protected]>
Greetings,

Here are my rather surprising results of different compression settings in Dar.  I always rebooted before starting each test.  My hardware is a Pentium III 533 MHz, 640 MB RAM, and two 7200 RPM IDE hard drives.  Each test was a complete backup of a basic Suse 8.2 linux install.  I made the backups onto the second hard drive.

No compression
dar -c /mnt/backup/nozip -R / -P var/ -P proc/ -P mnt/backup -D
Time:	10 minutes
Size:	1,499,000,000

Gzip
dar -c /mnt/backup/gzip2 -z -R / -P var/ -P proc/ -P mnt/backup/ -D
Time: 70 minutes
Size:	614,000,000

Gzip (Don't compress *.gz or *.bz2)
dar -c /mnt/backup/gzip-skip -z -R / -P var/ -P proc/ -P mnt/backup/ -D -Z *.gz -Z *.bz2
Time:	72 minutes
Size:	617,000,000

Bzip2
dar -c /mnt/backup/bzip2 -y -R / -P var/ -P proc/ -P mnt/backup/ -D
Time:	44 minutes
Size:   591,000,000

Bzip2 (Don't compress *.gz or *.bz2)
dar -c /mnt/backup/bzip2-skip -y -R / -P var/ -P proc/ -P mnt/backup/ -D -Z *.gz -Z *.bz2
Time:	40 minutes
Size:	589,000,000

These results show that Bzip2 (skip compressed files) appears to be the better compression choice.  I have not tested perfomance during a restore.  

Please comment on these results, and compare with your experiences.  Theoretically, Bzip2 should have been much slower, with a small advantage in compressed size.  

Tristan Rhodes


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