On 2019-09-09 11:29 a.m., Graham Cobb wrote: > and does anyone really care about > defrag any more?). >
Err, yes, yes absolutely. I don't have any issues with the current btrfs defrag implementions, but it's *vital* for btrfs. (which works just as the OP requested, as far as I can tell, recursively for a subvolume) Just booting Windows on a BTRFS virtual image, for example, will create almost 20,000 file fragments. Even on SSD's, you get into problems trying to work with files that are over 200,000 fragments. Another huge problem is rsync --inplace. which is perfect backup solution to take advantage of BTRFS snapshots, but fragments larges files into tiny pieces (and subsequently creates files that are very slow to read.).. for some reason, autodefrag doesn't catch that one either. But the wiki could do a beter job of trying to explain that the snapshot duplication of defrag only affects the fragmented portions. As I understand, it's really only a problem when using defrag to change compression.
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