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


More information about the freebsd-stable mailing list