On 2017年09月05日 09:05, Marc MERLIN wrote:
Ok, I don't want to sound like I'm complaining :) but I updated
btrfs-progs to top of tree in git, installed it, and ran it on an 8TiB
filesystem that used to take 12H or so to check.

How much space allocated for that 8T fs?
If metadata is not that large, 10min is valid.

Here fi df output could help.

And, without --repair, how much time it takes to run?


It finished in maybe 10mn, just 10mn! :)
gargamel:/var/local/src/btrfs-progs# btrfs check --repair /dev/mapper/dshelf1
enabling repair mode
Checking filesystem on /dev/mapper/dshelf1
UUID: 36f5079e-ca6c-4855-8639-ccb82695c18d
checking extents
Fixed 0 roots.
checking free space cache
cache and super generation don't match, space cache will be invalidated
checking fs roots
checking csums
checking root refs
found 11674263347200 bytes used, no error found
total csum bytes: 11384482936
total tree bytes: 13704495104
total fs tree bytes: 724729856
total extent tree bytes: 482639872
btree space waste bytes: 1167025205
file data blocks allocated: 12041456693248
  referenced 12063146434560

This is great news, but can I trust that the program worked properly and
indeed that my filesystem is fully clean?

Normally we rely on btrfs-progs selftest to make sure fsck works.
But maybe we could cross check original mode and lowmem mode.

Or at this point if I'm not running --mode=lowmem, the regular mode is
really doesn't check much and only lowmem can do a proper check? (even
though it can't fix problems once it finds them)

No, original mode is still the core (although code is not that elegant), please consider lowmem mode as a corner case for guys with small memory (without swap) but want to check super large fs.

So if it turns out to be a bug, we must fix it.

Thanks,
Qu

Thanks
Marc

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