5:58 a.m.
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On 07/11/2013 02:45 PM, Piotr Szubiakowski wrote:
> On 07/11/2013 12:52 PM, Piotr Szubiakowski wrote:
>>
>>>> The way that oVirt manage storage domains accessed via FC is very
>>>> smart.
>>>> There is separate logical volume for each virtual disk. But I
>>>> think that
>>>> logical volume at the same time could be "touched" only by one
>>>> host. Is
>>>> it possible that two host access read/write the same logical
>>>> volume and
>>>> there is no data corruption?
>>>
>>> hence a shared disk over block storage using LVM must be
>>> pre-allocated, so no LV changes (lv extend) would be needed.
>>> (also, it cannot have snapshots, since it would become qcow)
>>
>> Ok, but this is the hypervisor view. For a guest OS this LV is
>> normal RAW block device. I wonder if someone test this feature and
>> access shared disk from many VM's at the same time?
> I did a brief tests - 3 vms, shared disk, cman/pacemaker + gfs2 - had
> no problems using it, no data corruption. although that was only
> basic tests, like create/move/delete files, no extensive usage/stress
> or something like that.
Thanks Yuri,
Is fencing handled by the cman/pacemaker? I read about the fanced
daemon and it seems to be difficult to use it together with oVirt.
Piotr
yea, fencing handled by pacemaker, stonith resource fence_rhev -
parameters according to man page, with one exception - had to add
/pcmk_host_list="vmname" /additional parameter, so pacemaker would know
that this stonith device belongs to that VM.
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<div class="moz-cite-prefix">On 07/11/2013 02:45 PM, Piotr
Szubiakowski wrote:<br>
</div>
<blockquote cite="mid:51DE8CD5.2030806@nask.pl"
type="cite">
<br>
<br>
<blockquote type="cite">On 07/11/2013 12:52 PM, Piotr Szubiakowski
wrote:
<br>
<blockquote type="cite">
<br>
<blockquote type="cite">
<blockquote type="cite">The way that oVirt manage storage
domains accessed via FC is very smart.
<br>
There is separate logical volume for each virtual disk.
But I think that
<br>
logical volume at the same time could be "touched" only by
one host. Is
<br>
it possible that two host access read/write the same
logical volume and
<br>
there is no data corruption?
<br>
</blockquote>
<br>
hence a shared disk over block storage using LVM must be
pre-allocated, so no LV changes (lv extend) would be needed.
<br>
(also, it cannot have snapshots, since it would become qcow)
<br>
</blockquote>
<br>
Ok, but this is the hypervisor view. For a guest OS this LV is
normal RAW block device. I wonder if someone test this feature
and access shared disk from many VM's at the same time?
<br>
</blockquote>
I did a brief tests - 3 vms, shared disk, cman/pacemaker + gfs2
- had no problems using it, no data corruption. although that
was only basic tests, like create/move/delete files, no
extensive usage/stress or something like that.
<br>
</blockquote>
<br>
Thanks Yuri,
<br>
Is fencing handled by the cman/pacemaker? I read about the fanced
daemon and it seems to be difficult to use it together with oVirt.
<br>
<br>
Piotr
<br>
</blockquote>
yea, fencing handled by pacemaker, stonith resource fence_rhev -
parameters according to man page, with one exception - had to add
<em>pcmk_host_list="vmname"
</em>additional parameter, so pacemaker would know that this stonith
device belongs to that VM.<br>
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