[Gluster-devel] client crash with write-behind, other oddities in latest 1.4 tla

Brent A Nelson brent at phys.ufl.edu
Tue Sep 16 16:15:25 UTC 2008

I've been looking for ways to speed up the performance of the new afr code 
in 1.4 (which is far slower writing, though presumably more correct).  I 
found that write-behind brings it to more normal speeds, and the 
new o-direct option of storage/posix seems to help quite a bit, too.

Unfortunately, I'm seeing some occasional client crashes when write-behind 
is used on the client (with or without o-direct), with dump output such as 
the following:


Even more puzzling, the o-direct option seems to require write-behind; 
disabling write-behind causes immediate I/O errors when attempting to 
write with o-direct enabled (restarting servers and client didn't help).

After then disabling o-direct on the servers and remounting, I discovered 
something still more puzzling; the performance was still pretty good, even 
though write-behind was now disabled on the client! Perhaps the effects of 
o-direct linger (even though all processes were restarted)?



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