On Sat, Dec 01, 2007 at 02:03:06PM -0500, Mark Nielsen wrote: > I think you'll get the same sort of thing if you gzip the file. I've > gzip'd some 20G xen images down to around 2G. AFAIR, this is just because sparse files appear as long sequences of zeros & thus compress wel - gzip isn't actually optimizing for sparseness. The trouble is that when you extract the file gunzip will fully allocate it filling with zeros. My original 1M file takes 4k # ls -lhs foo 4.0K -rw-r--r-- 1 root root 1.0M 2007-12-01 14:18 foo #gzip foo # ls -lhs foo.gz 8.0K -rw-r--r-- 1 root root 1.1K 2007-12-01 14:18 foo.gz Now when it uncompress it it takes up the full 1 MB :-( # gunzip foo.gz # ls -lhs foo 1.1M -rw-r--r-- 1 root root 1.0M 2007-12-01 14:18 foo You *always* want to use tar to preserve sparseness, and then gzip the tar file so you get optimal resource usage both on archiving & extracting. Dan. -- |=- Red Hat, Engineering, Emerging Technologies, Boston. +1 978 392 2496 -=| |=- Perl modules: http://search.cpan.org/~danberr/ -=| |=- Projects: http://freshmeat.net/~danielpb/ -=| |=- GnuPG: 7D3B9505 F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 -=| -- Fedora-xen mailing list Fedora-xen@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-xen
