[Engine-devel] the future of template cloning

[Livnat Peer]

On 17/01/12 10:46, Itamar Heim wrote:
> On 01/17/2012 10:32 AM, Omer Frenkel wrote:
>>
>>
>> ----- Original Message -----
>>> From: "Itamar Heim"<iheim at redhat.com>
>>> To: "Jon Choate"<jchoate at redhat.com>
>>> Cc: engine-devel at ovirt.org
>>> Sent: Monday, January 16, 2012 7:26:24 PM
>>> Subject: Re: [Engine-devel] the future of template cloning
>>>
>>> On 01/16/2012 06:16 PM, Jon Choate wrote:
>>>> On 01/16/2012 10:58 AM, Itamar Heim wrote:
>>>>> On 01/16/2012 05:46 PM, Jon Choate wrote:
>>>>>> On 01/16/2012 09:46 AM, Livnat Peer wrote:
>>>>>>> On 12/01/12 22:45, Ayal Baron wrote:
>>>>>>>>
>>>>>>>> ----- Original Message -----
>>>>>>>>> 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?
>>>>>>>> I see no relation between the two options.
>>>>>>>>
>>>>>>>> Scenario 1: I can create a VM with a single disk and create a
>>>>>>>> template from it.
>>>>>>>> I would still want to be able to clone the template in order to
>>>>>>>> provision VMs from it on different domains.
>>>>>>>>
>>>>>>>> Scenario 2: same thing with multiple disks on same domain.
>>>>>>>>
>>>>>>>> Scenario 3: I have a template with 2 disks on 2 different
>>>>>>>> domains
>>>>>>>> (domain A and domain B) and I want to have another copy of the
>>>>>>>> template on domain C and domain D
>>>>>>>>
>>>>>>> Hi Jon,
>>>>>>>
>>>>>>> After talking to Michael Pasternak it seems that we did not
>>>>>>> implemented
>>>>>>> copyTemplate in the REST API, it seems to be a gap that we have.
>>>>>>>
>>>>>>> This gap is playing in our favor, we can remove the copyTemplate
>>>>>>> verb
>>>>>>> and introduce copyDisk verb.
>>>>>>>
>>>>>>> The template disks can be copied to another SD.
>>>>>>> When creating a VM from template the user can choose per disk
>>>>>>> the
>>>>>>> destination SD (only SD with the disks are eligible candidates).
>>>>>> wait, when creating a VM from a template, the user won't get a
>>>>>> choice
>>>>>> will they? Won't the VM disks have to go on the same storage
>>>>>> domain as
>>>>>> the template disks they were created from?
>>>>>
>>>>> yes, but the template disks can be copied to multiple storage
>>>>> domains,
>>>>> so the user can choose for the VM/disk which storage domain to
>>>>> create
>>>>> them from (per storage domains that have copies of that disk)
>>>> OH! I totally misunderstood. So what you are saying is that a
>>>> template
>>>> can have N number of copies of the same disk each on a different
>>>> storage
>>>> domain. I had thought that if you wanted that type of situation you
>>>> would have multiple copies of the template itself too.
>>
>> yes, one copy of disk per domain though.
>>
>>>>
>>>> Just to be clear, does this mean that the plan is to phase out the
>>>> current clone template command and instead implementing a clone
>>>> disk
>>>> command so that a template can duplicate its disks individually?
>>>
>>> pretty much, yes.
>>> though i'd imagine 'clone template' would still be useful to have for
>>> the user. not sure if it implies core should expose it as well to
>>> allow
>>> easier usage at UI level for such a task.
>>
>> we can leave it untouched - means copyTemplate get 1 destination
>> domain, and copies all disks to it,
>> but i think it will be unusable (and problematic - what if one of the
>> disks already exists on the destination?),
> 
> then don't copy it, it is already there
> 

I agree with Omer, there is no reason to support copy template, if the
user wants to clone all the disks he can use multiple actions, we don't
need a specific verb for this.
If the UI chooses to expose such operation it will use the
multipleRunAction API which makes it easier to expose to the user
partial success, we could clone disk A and Disk B but Disk C failed etc.



>> what the user really wants is to specify which disks to copy
>> and destination per disk, and i don't see a reason to create a backend
>> command to do it
>>
>>> _______________________________________________
>>> Engine-devel mailing list
>>> Engine-devel at ovirt.org
>>> http://lists.ovirt.org/mailman/listinfo/engine-devel
>>>
> 
> _______________________________________________
> Engine-devel mailing list
> Engine-devel at ovirt.org
> http://lists.ovirt.org/mailman/listinfo/engine-devel