[Engine-devel] SharedRawDisk feature detail

[Maor]

On 02/12/2012 07:03 PM, Livnat Peer wrote:
> On 02/02/12 17:15, Maor wrote:
>> Hello all,
>>
>> The shared raw disk feature description can be found under the following
>> links:
>>   http://www.ovirt.org/wiki/Features/DetailedSharedRawDisk
>>   http://www.ovirt.org/wiki/Features/SharedRawDisk
>>
>> Please feel free, to share your comments.
>>
>> Regards,
>> Maor
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>> Engine-devel mailing list
>> Engine-devel at ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/engine-devel
> 
> Hi Maor,
> 
> - "when taking a VM snapshot, a snapshot of the shared disk will not be
> taken."
> I think it is worth mentioning that the shared disk will be part of the
> VM snapshot configuration. The disk will appear as unplugged.
Agreed, I changed it to the following:
when taking a vm snapshot, a snapshot of the shared disk should not be
taken, although it will be part of the VM snapshot configuration and the
disk will appear as unplugged.
> 
> - Move VM is deprecated in 3.1.
Right, I removed this anecdote from the wiki.
> 
> - It seems from the wiki that shared disk is not supported for template
> but is supported for VM pool.
> I am not sure how can we do that? iirc we create pool from template.
What I was thinking about, is that the administrator can take a VM from
the pool and attach it a shared disk, after the VM was created (for
testing).

The motivation for adding shared disk was that each entity that can be
added with a disk can also be added with shared disk.
Today, Administrator can add a disk to a VM from pool, which might be
wrong behaviour, so maybe its better not to support it...
> 
> What is the complexity of supporting shared disk in Templates? off the
> top of my head it seems like it is more complicated to block shared
> disks in templates than to support it. What do you think?
Implementation wize it might be less complex, the problem is the use
cases it raises, some of them which I'm thinking about are:
* If the disk will be deleted from the DC, should we remove it from the
template? or leave an indication in the template that there was a shared
disk there, maybe should not allow to delete the disk in the first
place, until it is unattached from the template?
* What do we want to do when creating a template from VM with shared
disk - Should User choose whether to create a template with/without the
shared disk?

Blocking shared disk from template means creating the template without
the shared disk, the implementation for it is to check if the disk is
shared or not.
I think that if GUI will support attaching shared disk to multiple VMs,
there is no strong use case for allowing adding shared disk to a template.
> 
> 
> Livnat
>