[CentOS] DRBD on a xen host: crash on high I/O

On Tue, 2009-07-28 at 20:11 +0200, Andrea Dell'Amico wrote:
> Hello,
> I have a couple of Dell 2950 III, both of them with CentOS 5.3, Xen,
> drbd 8.2 and cluster suite.
> Hardware: 32DB RAM, RAID 5 with 6 SAS disks (one hot spare) on a PERC/6
> controller.
> 
> I configured DRBD to use the main network interfaces (bnx2 driver), with
> bonding and crossover cables to have a direct link.
> The normal network traffic uses two different network cards.
> There are two DRBD resources for a total of a little less than 1TB.
> 
> When the two hosts are in sync, if I activate more than a few (six or
> seven) xen guests, the master server crashes spectacularly and reboots.
> 
> I've seen a kernel dump over the serial console, but the machine
> restarts immediately so I didn't write it down.

If you have an available pc, hook it up in place of the serial console
and start a terminal emulator, e.g. minicom or whatever you prefer, and
turn on full logging. This should save everyting in a file that you can
then review.

If it's a Windows based, just remember to get rid of the ^M with
dos2unix, or equivalent, after you send it to a *IX box.

I don't know anything about the rest of your problem, sorry.

> 
> Unfortunately I cannot experiment because I have production services on
> those machines (and they are working fine until I start drbd on the
> slave).
> 
> drbd configuration is attached.
> 
> Anybody has an idea of the problem? The crash is perfectly reproducible,
> and drbd seems to be the problem (maybe the Xen kernel helps?).
> 
> Thanks in advance,
> Andrea
> <snip sig stuff>

HTH
-- 
Bill