System deadlock when using mksnap_ffs
Greg Byshenk
freebsd at byshenk.net
Fri Nov 14 01:26:11 PST 2008
On Thu, Nov 13, 2008 at 05:08:10PM +0100, Greg Byshenk wrote:
> On Wed, Nov 12, 2008 at 08:42:00PM -0800, Jeremy Chadwick wrote:
>
> > The rest of the below information is good -- but I'm confused about
> > something: is there anyone out there who can use mksnap_ffs on a
> > filesystem (/usr is a good test source) and NOT experience this
> > deadlocking problem? Literally *every* FreeBSD box I have root access
> > to suffers from this problem, so I'm a little baffled why we end-users
> > need to keep providing debugging output when it should be easy as pie
> > for a developer to do "dump -0 -L -a -f /path/fs.dump /usr" and watch
> > their system wedge.
>
> As an answer to the question (and additional information), I am
> experiencing the problem, but not on all filesystems.
>
> This is under FreeBSD 7.1-PRERELEASE #7: Thu Nov 6 11:29:52 CET 2008,
> amd64 (from sources csup'ed immediately prior to the build).
>
> I have four filesystems used for data storage:
>
> /dev/da1p1 96850470 7866026 81236408 9% /export/mail
> /dev/da1p2 1937058312 972070320 810023328 55% /export/home
> /dev/da1p3 1937058312 79027008 1703066640 4% /export/misc
> /dev/da1p4 2598991534 271980564 2119091648 11% /export/spare
>
> I can successfully mksnap_ffs the first (smaller) partition, but an
> attempt to do so on any of the others causes a lock.
>
> Note: this is a lockup, not a "slow". The system becomes unresponsive
> to any input, and there is no hard drive activity, and this does not
> change over a period of more than 12 hours.
As a followup to my own post, after reading this discussion, I applied
the patches and rebuild my system last night.
As of today, with the patched ffs_snapshot.c, I can now make snapshots
of all the filesystems listed above. It takes rather a long time, but
that is to be expected, I think, and the snapshots finish normally.
--
greg byshenk - gbyshenk at byshenk.net - Leiden, NL
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