[OpenAFS] CopyOnWrite failed. Workarounds?

Friedrich Delgado Friedrichs 6delgado@informatik.uni-hamburg.de
Tue, 28 May 2002 16:06:11 +0200


On Sunday i sent a report about my whole home directory becoming orphaned.
Derrick J Brashear has guessed, that it may be the "CopyOnWrite failure" bug,
that several people on this list have experienced, however i could not prove this,
having lost the logfiles.

After reading several of those posts here and on openafs-devel, i am now pretty sure that i
suffered from the same bug, because apart from the missing logfile entry, the behaviour
on my box was pretty much the same as reported by Marco Foglia in <3C8F30DB.73BAD2EE@psi.ch>
and Matthew N. Andrews in <BJEHJHBBLPOFPKCANEMGIEABCAAA.mnandrews@lbl.gov> on the openafs-devel

Especially since the first report from Marco Foglia dates back to 10/31/2001, and i intend
to use openafs on my home box and at work in a minor installation, which might serve as
a testbed for a larger installation lateron, i'd prefer not to wait for a fix, but rather
like to know which workaround seems viable, especially if you want to have regular backups...

If i fail to resolve this issue, i'd have to decide not to use afs, since regular lossage
of this dimension is clearly not desirable. ;-)

>From the other posts, i noticed a few points which might be helpful:
	- Don't use backup volumes. Marco Foglia clearly stated that the problem never
		arises when the backup volumes are removed.
	  This probably means that in a smaller installation i will take regular dumps
	  directly from the home volumes, instead of using the backup volumes. Are there
	  any negative side-effects to be expected, i.e. because a mail delivery process
	  might hang in iowait for a long time, processes might timeout, etc.?
	- I can't see clearly whether using a single threaded fileserver (is this the
	  same as the lwp fileserver?) will help. Several posters hinted in this direction
	  but hoffman@cs.pitt.edu in <200203182232.g2IMWil23214@frack.cs.pitt.edu> stated
	  that it might make things worse.

What else could help me get around the problem, whilst retaining most of afs's functionality?

Best Regards
		Friedrich Delgado Friedrichs