On Thu, 2002-08-22 at 16:43, Greg Freemyer wrote:
> All,
>
> I have not been successful at getting reliable Read-Only snapshots of XFS via
> LVM. Since XFS is being used in Enterprise quality applications, I suggest
> this is a major shortcoming that should be prioritized.
>
> BTW: Are there any snapshot related tests in the XFS regression tests?
No, there aren't. Frankly, snapshot has not gotten a lot of attention
lately.
> When a failure occurs the lvcreate --snapshot command will freeze up.
If that's the failure, looking at a kdb backtrace of the "stuck" process
would be helpful, and might give us an idea of where to look.
Testing a CVS kernel for the same behavior would also be a good
datapoint.
> A manually entered xfs_freeze -u will release the lvcreate. (The VFS-lock
> patch effectively is calling xfs_freeze -f internally prior to starting the
> snapshot process.)
> FYI: Adrian Head believes that the VFS-lock patch is more reliable than not
> having it and wrapping the lvcreate --snapshot call with explicit xfs_freeze
> calls. I have not tried that.
If things are working as intended, that should not be the case - the end
result should be that xfs runs the same code, whether you did it via a
manual userspace command, or the automatic vfs-lock patch.
Sending some debug output from kdb would help - but also, take a look at
that list of work Steve posted today, and realize that there are lots of
things going on at the moment. :)
Thanks,
-Eric
--
Eric Sandeen XFS for Linux http://oss.sgi.com/projects/xfs
sandeen@xxxxxxx SGI, Inc. 651-683-3102
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