On Tue, Aug 14, 2012 at 12:50 PM, Michael Hampicke <gentoo-u...@hadt.biz> wrote: > Am 14.08.2012 19:42, schrieb Volker Armin Hemmann: >> Am Dienstag, 14. August 2012, 13:21:35 schrieb Jason Weisberger: >>> Sure, but wouldn't compression make write operations slower? And isn't he >>> looking for performance? >> >> not really. As long as the CPU can compress faster than the disk can write >> stuff. >> >> More interessting: is btrfs trying to be smart - only compressing >> compressible >> stuff? >> > > It does do that, but letting btrfs check if the files are already > compressed, if you know, that they are compressed, is a waste of cpu > cycles :) >
Also look into the difference between compress and compress-force[0]. I wonder how much overhead checking whether or not to compress a file costs. I use mount options similar to Helmut and get great results: defaults,autodefrag,space_cache,compress=lzo,subvol=@,relatime But most of my data is compressible. Compression makes such a huge difference, it surprises me. Apparently on this Ubuntu system it automatically makes use of all files on / as a subvolume in "@". Interesting. Anyway, btrfs-progs does include basic fsck now but I wouldn't use it for anything serious[1]. [0] https://btrfs.wiki.kernel.org/index.php/Mount_options [1] https://btrfs.wiki.kernel.org/index.php/Btrfsck
