On 11/12/2013 10:30 AM, joystick wrote:
On 11/11/2013 19:52, Justin Piszcz wrote:
Wait so that mismatches grow again a couple of thousands, then I suggest
you really do what I wrote in my previous email.
If you can afford to bring the system offline then it's really easy
because you can find all mismatching files in one shot
- wait for mismatch_cnt reach 2000 at least (the more, the better), then
reboot machine with a livecd
- mount RAID
- mount the filesystem readonly
- (very important or it will resync) activate bitmap for raid1,
preferably with small chunksize
- fail 1 drive so to degrade raid1
- drop caches with blockdev --flushbufs on the md device such as
/dev/md2, on the two underlying partitions such as /dev/sd[ab]2, and
maybe even on the two disk holding then such as /dev/sd[ab] (I'm not
really sure what is the minimum needed) ; and also echo 3 >
/proc/sys/vm/drop_caches
- recursive md5sum for all files of the filesystem (something like find
-type f -print0 | xargs -0 md5sum (untested)) > redirect stdout to a
file on another filesystem
- reattach drive with --re-add, let it resync the differences using the
bitmap (there shouldn't be any, should complete immediately)
- fail the other drive
- drop all caches again
- again find | md5sum , redirected to another file on another filesystem
- reattach drive with --re-add
now analyze differences between md5sums. Those are the files which are
different in the two legs of the RAID, and they shouldn't be (aka
corruption).
Find preferably humanly readable text files which are sequentially
written, such as log files. It is more difficult to understand what's
wrong for files changed in the middle such as database files, or binary
files.
If you have available disk space, you might run ql-fstest (possibly in
combination) with the above method.
https://bitbucket.org/aakef/ql-fstest
Right now it does not support yet to restart it and to verify existing
files, but I'm going to add this, either this evening or on Thursday.
Cheers,
Bernd
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