[Users] which file system for shared disk?

[Itamar Heim]

On 07/11/2013 05:38 AM, Shu Ming wrote:
> 2013-7-11 1:43, Itamar Heim:
>> On 07/10/2013 05:33 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.
> By using "pre-allocated" here, even for qcow on KVM? If it is
> pre-allocated, there is no benefit to use qcow.
>
>> (also, it cannot have snapshots, since it would become qcow)
> Why it can not have snapshots? I think qcow on the block device can also
> have snapshots.

of course, and we use it all the time, but not for shared disk, since 
then you'd need to sync the qcow metadata changes between the two active 
VMs writing to it