[DRBD-user] kernel crash when secondary disappears. centos 5.3 kernel-xen issue? (fwd)

Tom Brown wc-linbit.com at vmail.baremetal.com
Fri Apr 17 03:38:42 CEST 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


>
> Simon Graham explained an interesting effect when using scatter gather
> and DRBD and xen...

That seems to be this thread:
    http://www.gossamer-threads.com/lists/drbd/users/16962

unfortunately, in that case, Valentin apparently reported good results with
protocol C and this tweak:

   ethtool -K xenbr0 sg off

I can't get that. Even when using

    for if in eth0 peth0 virbr0 xenbr0 ; do
       ethtool -K $if rx off tx off sg off
    done


I DO seem to get a slightly more stable config... in 
fact, it sometimes seems to be stable until I bring the secondary back 
online, at which point I get a crash that looks _very_ similar to the 
initial one.

But, using protocol A is robust... (but slow?).

hhmm, yes. I just managed to crash the box during a resync
(proto C). I have the trace for that too if it is relevent.
(drbd.take4)

hhmm, I'm not convinced this test config is at all stable under
protocol C. I wanted to do a speed test, but can't keep it alive long 
enough :(

Anyhow, I need to put this down for now, I'm seriously in need of some 
exercise.

-Tom



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