[Engine-devel] Gluster Volume asynchronous tasks

[Itamar Heim]

On 08/21/2013 12:46 AM, Sahina Bose wrote:
>
> On 08/20/2013 04:00 AM, Itamar Heim wrote:
>> On 08/12/2013 06:09 AM, Sahina Bose wrote:
>>>
>>> On 08/12/2013 03:28 PM, Yair Zaslavsky wrote:
>>>>
>>>> ----- Original Message -----
>>>>> From: "Sahina Bose" <sabose at redhat.com>
>>>>> To: "Eli Mesika" <emesika at redhat.com>
>>>>> Cc: "engine-devel" <engine-devel at ovirt.org>, arch at ovirt.org
>>>>> Sent: Monday, August 12, 2013 11:51:15 AM
>>>>> Subject: Re: [Engine-devel] Gluster Volume asynchronous tasks
>>>>>
>>>>>
>>>>> On 08/12/2013 01:21 PM, Eli Mesika wrote:
>>>>>> ----- Original Message -----
>>>>>>> From: "Sahina Bose" <sabose at redhat.com>
>>>>>>> To: "engine-devel" <engine-devel at ovirt.org>, arch at ovirt.org,
>>>>>>> "Michael
>>>>>>> Pasternak" <mpastern at redhat.com>
>>>>>>> Sent: Monday, August 12, 2013 8:41:55 AM
>>>>>>> Subject: [Engine-devel] Gluster Volume asynchronous tasks
>>>>>>>
>>>>>>> Hi all,
>>>>>>>
>>>>>>> We are working on a feature to add support to start and monitor
>>>>>>> gluster
>>>>>>> volume asynchronous tasks (like rebalancing a gluster volume,
>>>>>>> removing
>>>>>>> brick from volume ) from the oVirt engine.
>>>>>>>
>>>>>>> The operations can be started from the Volumes tab or the Bricks
>>>>>>> sub-tab
>>>>>>> using the Rebalance, Remove options.
>>>>>>> These are long running operations which can be monitored using a
>>>>>>> task id
>>>>>>> returned from Gluster. We are planning to add the monitoring in the
>>>>>>> existing Task sub tab
>>>>>>>
>>>>>>> The feature description and User flows are at
>>>>>>> http://www.ovirt.org/Features/Gluster_Volume_Asynchronous_Tasks_Management
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> The detailed design (including REST API design) is at
>>>>>>> http://www.ovirt.org/Features/Detailed_Gluster_Volume_Asynchronous_Tasks_Management.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> I would really appreciate if you could review and provide your
>>>>>>> valuable
>>>>>>> feedback.
>>>>>> I Sahina
>>>>>> Why not using 6the External Tasks feature introduced for 3.3 for
>>>>>> those
>>>>>> Gluster tasks ???
>>>>>> http://www.ovirt.org/Features/Design/DetailedExternalTasks
>>>>> Hi Eli,
>>>>>
>>>>> We still want to be able to start and stop these operations from the
>>>>> engine.
>>>>> So, when a user wants to say, rebalance a volume, they would go select
>>>>> the volume and click on Rebalance Start.
>>>>> This would then call the BLL command to start rebalance which will
>>>>> invoke the corresponding vdsm verb to start the rebalance on the
>>>>> volume.
>>>>> This is the same as existing flow for other commands. The only
>>>>> difference is the vdsm verb will return the task id from gluster, for
>>>>> the rebalance operation that was started. And we will monitor the
>>>>> progress of the task using the gluster task id (by calling a gluster
>>>>> command)
>>>>>
>>>>> I'm not sure how ExternalTasks would fit in here? I was thinking of
>>>>> using ExternalTask support for adding Job/Steps to engine when the
>>>>> operation is started outside of engine, that is, from Gluster CLI.
>>>>> Please correct me if I'm missing something.
>>>> Does this mean that from Gluster CLI you will not try and invoke the
>>>> rebalance command ?
>>>> (I mean, I should either use Gluster CLI or Engine's REST API?)
>>> Rebalance volume command could be invoked in any of the following ways:
>>> 1. From the console UI (clicking on Rebalance as shown in
>>> http://www.ovirt.org/Features/Gluster_Volume_Asynchronous_Tasks_Management#Rebalance_Volume)
>>>
>>>
>>> 2. Using REST API
>>> 3. Outside of engine, from Gluster CLI - In such cases, the engine
>>> should detect that a user has triggered rebalance operation outside the
>>> engine, and allow the user to monitor progress of this from the engine.
>>> This is where, we need support to add a Job for an operation that was
>>> started externally, so that it can be seen in the Tasks tab.
>>
>> and still, it should be considered an internal task, since the engine
>> is managing it / detected it.
>>
>
> Itamar, yes, you are right. This would need to be treated as an internal
> task as the engine needs to be able to stop it and also monitor it. We
> would probably need a similar mechanism as external task injection, to
> add a Job for the task started from gluster CLI.
>
>

even if it was started from CLI, wouldn't it be better if engine 
detected it, and still treated it as an internal task, allowing to 
cancel it, etc.?