Different Compression Utilities

[shanenin]

I have been messing around tarring and compressing my system, for backup purposes. I was told to try rzip, it is supposed to be supurior in some ways, but has some other limitations. I used 'du -h' to collect all of the needed data. below are the results I got

here are some results of compressing my ubuntu system

3.1gb size of partition uncompressed

1.9gb size of bzip2 compressed system

1.7gb size of rzip compressed system

those are not compressed as much as I thought they would have been. When I originally compressed my gentoo base system using bzip2, it went down from 1.4gb all the way to 168mb, that is a compression ratio of about 8. when compressing my ubuntu full system the compression ratio was about 1.5 to 1.7 depending on wheter using bzip2 or rzip.

I wonder why I got about 5 times better compression doing my gentoo base system, over compressing my ubuntu full system.

[shanenin]

I wonder why I got about 5 times better compression doing my gentoo base system, over compressing my ubuntu full system.

oops, part of the reason was I had a bout 1 gb of compressed files in ubuntu install. Now that those are deleted I am getting better results.

using rzip I compressed my 1.8 gb ubunutu install down to 457 mb

I am in the process of using bzip2, I expect the results to be a little higher

[jcl]

It's possible that the mix of filetypes in your Ubuntu and Gentoo installs is very different. Generally speaking I would expect that as a proportion of non-text files (executables, libraries, images, etc) went up, the compression ratio would go down (that it, toward 1:1). Ubuntu likely has a much larger proportion of binaries than Gentoo.

You may want to poke around your Gentoo install and see if it has any large stashes of the source code that are compressing well. The build directories in /var/tmp/portage/, for example, can eat a tremendous amount of disk space in some circumstances, but should compress nicely. As of a few minutes ago I had ~5.5GiB of gunk left over from builds under there. (That's abnormal for Gentoo as far as I know; I think it I had noclean set in FEATURES for a while when I was having trouble with some packages and needed to patch them by hand. Still, I think you do accumulate cruft as time goes on.)

Edit: Hahaha. I wrote the post and then spent 20 minutes fiddling with Gentoo looking for the aforementioned source stashes before I posted.

Edited May 15, 2005 by jcl

[shanenin]

I just checked /var/tmp/portage, and I have about 500 mbs of stuff, I am guessing most of that is source code. As the bianaries are being built, wouldn't they also be left behind in /var/tmp/portage

my bzip resultsa came in at 525mb

so rzip at 457mb was a little better :-|