[Engine-devel] the future of template cloning

[Itamar Heim]

On 01/12/2012 04:04 PM, Ewoud Kohl van Wijngaarden wrote:
> On Thu, Jan 12, 2012 at 03:56:05PM +0200, Itamar Heim wrote:
>> On 01/12/2012 03:50 PM, Jon Choate wrote:
>>>> On Thu, Jan 12, 2012 at 8:44:56PM, Itamar Heim wrote:
>>>> On 01/12/2012 02:19 PM, Jon Choate wrote:
>>>>> We are going to be able to store the disks for a template on
>>>>> different storage domains due to the multiple storage domain
>>>>> feature.  Cloning a template will still be possible, but will it
>>>>> provide any value?  Thoughts?
>>>>
>>>> you would want to clone the disks to the storage domains you would
>>>> want to create thinly provisioned disks from for this template.
>>>>
>>>> so a template could have disk1 and disk2 on SD1, then disk2 cloned to
>>>> SD2 to allow creating a VM with thin COW for disk2 on SD2 as well.
>>>>
>>>
>>> But with the ability to create a template with disk 1 on SD1 and
>>> disk2 on SD2 is that still a compelling feature?
>>
>> yes, since I may want to create virtual machines from this template
>> where the 2nd disk is sometimes on SD1 and sometime on SD2 (just
>> like today, where i can instantiate a VM from the template on
>> multiple storage domains)
>> The new feature will just allow me to not clone all the disks of the
>> template to all storage domains, rather a subset.
> But would this be interesting to the user or would it be better to do
> this transparently so the user doesn't have to care? The user just wants
> to use template X and store it on storage domain Y with COW. The system
> could deduce it has to be cloned first and not bother the user.

that means a user would be able to affect where the template resides. 
user may not have permissions to do so, would require to configure which 
quota this will happen from, etc.
so I'm not sure doing it implicitly based on a user trying to create a 
disk on a domain.