[DRBD-user] Kernel hung on DRBD / MD RAID

Andreas Bauer ab at voltage.de
Tue Feb 14 12:21:07 CET 2012

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


From:	Lars Ellenberg <lars.ellenberg at linbit.com>

> Ok, corrected to 8.3.11:
> > > Kernel 3.1.0 / DRBD 8.3.11
> 
> Nothing directly DRBD related in the stack traces.

Yes, makes sense for the md_resync, but what for the KVM process? It does access its device via DRBD, so is the stacktrace incomplete? (missing DRBD layer?).

> But you have one kvm in:
> kernel: [2009644.546925]  [<ffffffffa00939d1>] ?  wait_barrier+0x87/0xc0 [raid1]
> and md1_resync in 
> kernel: [2009644.547433]  [<ffffffffa0093917>] ?  raise_barrier+0x11a/0x14d 
> [raid1]
> 
> Looks like MD is stepping on it's own toes there.

Stepping on one's own toes is something one isn't supposed to do, right? ;-)

I might raise the issue with the MD developpers but at the moment I am still confused why DRBD did behave like it did. How would DRBD behave when the backing device blocks hard?

regards,

Andreas



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