Re: Latest bobtail branch still crashing KVM VMs in bh_write_commit()

[Josh Durgin <josh.durgin@inktank.com>]

On 03/20/2013 01:19 PM, Josh Durgin wrote:
> On 03/20/2013 01:14 PM, Stefan Priebe wrote:
>> Hi,
>>
>>> In this case, they are format 2. And they are from cloned snapshots.
>>> Exactly like the following:
>>>
>>> # rbd ls -l -p volumes
>>> NAME                                                         SIZE
>>> PARENT                                           FMT PROT LOCK
>>> volume-099a6d74-05bd-4f00-a12e-009d60629aa8                 5120M
>>> images/b8bdda90-664b-4906-86d6-dd33735441f2@snap   2
>>>
>>> I'm doing an OpenStack boot-from-volume setup.
>>
>> OK i've never used cloned snapshots so maybe this is the reason.
>>
>>>> strange i've never seen this. Which qemu version?
>>>
>>> # qemu-x86_64 -version
>>> qemu-x86_64 version 1.0 (qemu-kvm-1.0), Copyright (c) 2003-2008
>>> Fabrice Bellard
>>>
>>> that's coming from Ubuntu 12.04 apt repos.
>>
>> maybe you should try qemu 1.4 there are a LOT of bugfixes. qemu-kvm does
>> not exist anymore it was merged into qemu with 1.3 or 1.4.
>
> This particular problem won't be solved by upgrading qemu. It's a ceph
> bug. Disabling caching would work around the issue.
>
> Travis, could you get a log from qemu of this happening with:
>
> debug ms = 20
> debug objectcacher = 20
> debug rbd = 20
> log file = /path/writeable/by/qemu

If it doesn't reproduce with those settings, try changing debug ms to 1
instead of 20.

>  From those we can tell whether the issue is on the client side at least,
> and hopefully what's causing it.
>
> Thanks!
> Josh