[Gluster-devel] Simplify creation and set-up of meta-volume (shared storage)

[Shubhendu Tripathi]

Thanks Avra for the confirmation.

Regards,
Shubhendu

On 05/18/2015 02:04 PM, Avra Sengupta wrote:
> With this option, the volume will be created and explicitly mounted on 
> all the nodes, which are currently a part of the cluster. Please note 
> that new nodes added to the cluster will not have the meta volume 
> mounted explicitly.
>
> So in a case where the console tries to use the volume from a peer in 
> the cluster, which was added after the option was set it will not have 
> the mount available to it. Hence I feel its best that the console 
> continues with the explicit mounting, and showing explicit warning 
> during stop/remove-brick of the meta volume in console and allow the 
> operations.
>
> There is no other impact on the console, as far as this feature is 
> concerned.
>
> Regards,
> Avra
>
> On 05/18/2015 09:27 AM, Shubhendu Tripathi wrote:
>> Avra,
>>
>> We are planning to provide mounting of meta volume on the nodes of 
>> the cluster from Console as part of volume syncing and addition of 
>> new nodes to the cluster. Looks like if this option is set, the 
>> explicit mounting of the meta volume from console is not required and 
>> it would be taken care by gluster.
>>
>> Currently we show explicit warning during stop/remove-brick of the 
>> meta volume in console and allow the operations. I dont feel there 
>> would be any impact due to new feature.
>>
>> Kindly let us know if any other impact on console or we need to take 
>> care of anything else as result of this feature.
>>
>> Thanks and Regards,
>> Shubhendu
>>
>> On 05/15/2015 07:30 PM, Avra Sengupta wrote:
>>> Hi,
>>>
>>> A shared storage meta-volume is currently being used by 
>>> snapshot-scheduler, geo-replication, and nfs-ganesha. In order to 
>>> simplify the creation and set-up of the same, we are introducing a 
>>> global volume set option(cluster.enable-shared-storage).
>>>
>>> On enabling this option, the system analyzes the number of peers in 
>>> the cluster, which are currently connected, and chooses three such 
>>> peers(including the node the command is issued from). From these 
>>> peers a volume(gluster_shared_storage) is created. Depending on the 
>>> number of peers available the volume is either a replica 3 volume(if 
>>> there are 3 connected peers), a replica 2 volume(if there are 2 
>>> connected peers), or a single brick volume(if there is only one node 
>>> in the cluster). "/var/run/gluster/ss_brick" serves as the brick 
>>> path on each node for the shared storage volume. We also mount the 
>>> shared storage at "/var/run/gluster/shared_storage" on all the nodes 
>>> in the cluster as part of enabling this option.
>>>
>>> Once the volume is created, and mounted the maintainance of the 
>>> volume like adding-bricks, removing bricks etc., is expected to be 
>>> the onus of the user.
>>>
>>> On disabling the option, we provide the user a warning, and on 
>>> affirmation from the user we stop the shared storage volume, and 
>>> unmount it from all the nodes in the cluster.
>>>
>>> These are achieved with hook-scripts as part of the volume set 
>>> option. If anyone is interested in having a look at the patch, it's 
>>> available for review at http://review.gluster.org/#/c/10793/ . If 
>>> there is any feedback and suggestion regarding the same, please feel 
>>> free to share it.
>>>
>>> Regards,
>>> Avra
>>>
>>> _______________________________________________
>>> Gluster-devel mailing list
>>> Gluster-devel at gluster.org
>>> http://www.gluster.org/mailman/listinfo/gluster-devel
>>
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