[Lustre-discuss] MDS overload, why?

[Arne Brutschy]

Hi,

8GB of ram, 2x 4core Intel Xeon E5410 @ 2.33GHz

Arne

On Fr, 2009-10-09 at 12:16 +0200, Michael Kluge wrote:
> Hi Arne,
> 
> could be memory pressure and the OOM running and shooting at things. How
> much memory does you server has?
> 
> 
> Michael
> 
> Am Freitag, den 09.10.2009, 10:26 +0200 schrieb Arne Brutschy:
> > Hi everyone,
> > 
> > 2 months ago, we switched our ~80 node cluster from NFS to lustre. 1
> > MDS, 4 OSTs, lustre 1.6.7.2 on a rocks 4.2.1/centos 4.2/linux
> > 2.6.9-78.0.22.
> > 
> > We were quite happy with lustre's performance, especially because
> > bottlenecks caused by /home disk access were history.
> > 
> > Saturday, the cluster went down (= was inaccessible). After some
> > investigation I found out that the reason seems to be an overloaded MDS.
> > Over the following 4 days, this happened multiple times and could only
> > be resolved by 1) killing all user jobs and 2) hard-resetting the MDS.
> > 
> > The MDS did not respond to any command, if I managed to get a video
> > signal (not often), load was >170. Additionally, 2 times kernel oops got
> > displayed, but unfortunately I have to record of them.
> > 
> > The clients showed the following error:
> > > Oct  8 09:58:55 majorana kernel: LustreError: 3787:0:(events.c:66:request_out_callback()) @@@ type 4, status -5  req at f6222800 x8702488/t0 o250->MGS at 10.255.255.206@tcp:26/25 lens 304/456 e 0 to 1 dl 1254988740 ref 2 fl Rpc:N/0/0 rc 0/0
> > > Oct  8 09:58:55 majorana kernel: LustreError: 3787:0:(events.c:66:request_out_callback()) Skipped 33 previous similar messages
> > 
> > So, my question is: what could cause such a load? The cluster was not
> > exessively used... Is this a bug or a user's job that creates the load?
> > How can I protect lustre against this kind of failure?
> > 
> > Thanks in advance,
> > Arne 
> > 
-- 
Arne Brutschy
Ph.D. Student                    Email    arne.brutschy(AT)ulb.ac.be
IRIDIA CP 194/6                  Web      iridia.ulb.ac.be/~abrutschy
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