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On 12/17/2015 04:49 AM, li.yuanzhen at zte.com.cn wrote:
> Hi all,
>
>   I'd like to start discussion on whether the servicegroup in Cinder
> is necessary.
>  
>   Recently, cinder can only support db driver, and doesn't have
> servicegroup concept.
>   our team wants to implement the servicegroup feature using on
> tooz[1] library. Like nova[2], when the state of service is required,
> it can be got through servicegroup.
>  
>   Besides, due to the cinder-volume-active-active-support[3] merged,
> we think it makes the Service Group do more.
>  
>   Before the cinder-volume-active-active-support was proposed, Cinder
> has no concept of cluster. Therefore, we have a doubt that, if without
> cinder-volume-active-active-support, is it necessary to add feature of
> servicegroup?
>  
>   Any comments or suggestions?
>  
>   [1]
> https://github.com/openstack/tooz/blob/master/doc/source/tutorial/group_membership.rst
>
>   [2]
> https://github.com/openstack/nova-specs/blob/master/specs/liberty/approved/service-group-using-tooz.rst
>
>   [3]
> https://github.com/openstack/cinder-specs/blob/master/specs/mitaka/cinder-volume-active-active-support.rst
>
>  
>  
>   Best Regards,
>   Janice

Hi,

It will not be possible to use A/A HA configuration of cinder-volume
service with LVM driver. According to latest User Survey [1] this driver
is running in 22% of deployments. ZooKeeper service groups will be still
useful there, as it will allow scheduler to know about failed
services/nodes much quicker and prevent from scheduling volumes there.

As we have initial Tooz integration [2] already merged for locking
purposes, I think that if we'll be able to implement SG in a
non-intrusive manner (without changing the default behavior) it would be
an interesting option for some deployments.

[1] http://www.openstack.org/assets/survey/Public-User-Survey-Report.pdf
[2] https://review.openstack.org/#/c/183537/