[Engine-devel] Gluster Volume asynchronous tasks

[Itamar Heim]

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.