On Tue, Aug 20, 2013 at 4:56 PM, Petr Soukup <sou...@simplia.cz> wrote:
> I am using ceph filesystem through ceph-fuse to store product photos and most 
> of the time it works great. But if there is some problem on ceph server, my 
> connected clients start acting crazy. Load on all servers with mounted ceph 
> jumps very high,  webserver and other services start to crash.
> I think, that if ceph server is irresponsive, system creates some queue and 
> as a result everything starts to fail. Simple solution for this is this 
> command:
> umount -fl /media/ceph && ceph-fuse /media/ceph
> After that everything gets to normal in a few minutes.
>
> Is it possible to set some timeout to ceph-fuse or something? It is much 
> better if reading photo from ceph will cause error than if everything fails 
> at once.
>
> I am using ceph 0.61.7 (today upgraded to 0.61.8), 2x OSD, 1x MDS and 4x mon 
> on different servers with Centos 6.4.
> I am going to try 0.67, but  I think that my main problem is configuration of 
> ceph-fuse mount. I also tried newer kernel with support for mount ceph, but 
> the kernel itself wasn't very stable.

What kind of problems are you seeing on the ceph server?
In general what you're seeing is the result of ceph-fuse behaving
optimistically: it expects that, if there is a problem on the cluster,
then the problem will be dealt with shortly. So while it has lots of
internal timeouts, it doesn't issue an error to clients unless it gets
one back from a server. Doing otherwise in a data-safe fashion would
be more or less impossible. If you want to add timeouts I bet you
could find a library that will intercept system calls and let you put
a timeout around them.
-Greg
Software Engineer #42 @ http://inktank.com | http://ceph.com
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