On Sat, May 11, 2013 at 05:57:11PM +0100, Tim Eggleston wrote: > > >Yes. The command just triggers the defragmentation which takes > >place in the > >background. Try a "sync" afterwards :) > > Sorry Martin, I should have specified that I wondered if it was like > the scrub operation in that respect, so I left it several hours > before running filefrag again (and seeing that the number of extents > was unchanged). Top and iostat also don't report any particular > activity immediately after running the defrag command, so it doesn't > look like much if anything is happening. > > By the way, this is on a filesystem mounted with -o autodefrag, > although per the docs I wasn't expecting the auto defragmentation to > work with the big VM images.
Hi Tim, Btrfs defrag tries to merge small extents in overall, so maybe the extents in your big VM images are large enough although there are 4000+ extents. And autodefrag is also only for small extents(like a write less then 16k). So, you may check if those extents are already big enough :) thanks, liubo > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
