On 01/22/2010 03:09 AM, Andreas Dilger wrote:
On 2010-01-21, at 20:37, Eric Sandeen wrote:
That sounds fine, as do mke2fs.conf hooks, as does a nice shipped script
to do background checking of snapshots.
But I still don't know why "You mounted your fs 20 times" is a good
proxy for "you had better check for corruption now." Have we so
little faith? :)
I've thought for quite a while that 20 mounts is too often, but I'm
reluctant to turn it off completely. I wouldn't object to increasing
it to 60 or 80.
At one time there was a patch that checked the state of the filesystem
at mount time and only incremented only 1/5 of the time (randomly) if
it was unmounted cleanly (not dirty, or not in recovery), but every
time if it crashed. The reasoning was that systems which crashed are
more likely to have memory corruption or software bugs, and ones that
shut down cleanly are less likely to have such problems.
I do like the snapshot idea, but also think that we need something will
not introduce random (potentially multi-hour or multi-day) fsck runs
after an otherwise clean reboot.
If we hit this with a combination of:
Reboot time:
(1) Try to mount the file system
(1) on mount failure, fsck the failed file system
While up and running, do a periodic check with the snapshot trick.
I think that would balance the fear that we have of creeping corruption
(or at least severe corruption) against the need to be speedy when
rebooting....
ric
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