Re: [Xen-users] Setting up XEN domU causes RAID5 to fail?

[Tony Lill <ajlill@xxxxxxxxxxxxxxxxxxx>]

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On 09/17/2012 02:22 AM, J. Roeleveld wrote:
> 
> On Mon, September 17, 2012 4:11 am, Tony Lill wrote:
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>> When I tried to upgrade my xen systems to a pvops xen/linux 
>> combo, I found that high disk I/O would cause disk errors and 
>> caused disks to be thrown out of the raid and all sorts of other 
>> badness. High of course, is a relative term. For one of my
>> boxes, copying a large file was enough, on another, it needed
>> something like running backups on several VMs simultaneously or
>> trying to start my VM's while rebuilding the raid.
>> 
>> FWIW, I went back to Xen 3.4.4 and the SLES1 xenlinux kernel and 
>> they've been rock solid.
> 
> This could be related to Xen version, but can also be related to 
> the use of desktop-drives in a RAID-configuration. Linux Software 
> raid is more tolerant than hardware raid, but it still doesn't
> like it if a disk dissappears/fails/acts up and will then kick it
> out.
> 
> I'm surprised there are no messages in the logs as I have always 
> seen at least a message from the raid-stack when a disk was thrown 
> out.

On the one box I got tons of messages, the other I got a error message
once, and the second time it just hung, after which I stopped trying.

> Are those drives SMART-compliant? If yes, try running a self-test 
> on those drives to see if there are any detectable problems.
> 
> Other possible cause: The PSU can't handle the load of all the 
> drives and the CPU going full speed.
> 
> You could also try to do some heavy load on those drives by 
> simultaneously copying "/dev/zero" to each of the drives.

The drives are smart compliant and healthy and have worked fine for
months/years, same as the PSU. The only difference is the XEN
technology. pvops, both self compiled and from the squeeze distro,
were totally unstable. On one box I could trash it just by copying a
large file. The xenlinux system is rock solid.

- -- 
Tony Lill, OCT,                    Tony.Lill@xxxxxxxxxxxxxxxxxxx
President, A. J. Lill Consultants                 (519) 650 0660
539 Grand Valley Dr., Cambridge, Ont. N3H 2S2     (519) 241 2461
- --------------- http://www.ajlc.waterloo.on.ca/ ----------------


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