Open Stack

On Sat, Jun 27, 2015 at 11:47 AM, Joshua Harlow <harlowja at outlook.com>
wrote:

> Duncan Thomas wrote:
>
>> We are working on some sort of distributed replacement for the locks in
>> cinder, since file locks are limiting our ability to do HA. I'm afraid
>> you're unlikely to get any traction until that work is done.
>>
>> I also have a concern that some backend do not handle load well, and so
>> benefit from the current serialisation. It might be necessary to push
>> this lock down into the driver and allow each driver to choose it's
>> locking model for snapshots.
>>
>
> IMHO (and I know this isn't what everyone thinks) but I'd rather have
> cinder (and other projects) be like this from top gear (
> https://www.youtube.com/watch?v=xnWKz7Cthkk ) where that toyota truck is
> virtually indestructible vs. trying to be a high-maintenance ferrari (when
> most openstack projects do a bad job of trying to be one). So, maybe for a
> time (and I may regret saying this) we could consider focusing on
> reliability, consistency, being the toyota vs. handling some arbitrary
> amount of load (trying to be a ferrari).
>
> Also I'd expect/think operators would rather prefer a toyota at this stage
> of openstack :) Ok enough analogies, ha.
>

​Well said Josh, I guess I've been going about this all wrong by not using
the analogies :)​


>
> -Josh
>
>
>> On 27 Jun 2015 06:18, "niuzhenguo" <niuzhenguo at huawei.com
>> <mailto:niuzhenguo at huawei.com>> wrote:
>>
>>     Hi folks,____
>>
>>     __ __
>>
>>     Currently we use a lockfile to protect the create operations from
>>     concurrent delete the source volume/snapshot, we use exclusive____
>>
>>     locks on both delete and create sides which will ensure that:____
>>
>>     __ __
>>
>>     __1.__If a create of VolA from snap/VolB is in progress, any delete
>>     requests for snap/VolB will wait until the create is complete.____
>>
>>     __2.__If a delete of snap/VolA is in progress, any create from
>>     snap/VolA will wait until snap/VolA delete is complte.____
>>
>>     __ __
>>
>>     but, the exclusive locks will also result in:____
>>
>>     __ __
>>
>>     __3.__If a create of VolA from snap/VolB is inprogress, any other
>>     create requests from snap/VolB will wait until the create is
>>     complete. ____
>>
>>     __ __
>>
>>     So the create operations from same volume/snapshot can not process
>>     on parallel, please reference bp [1].____
>>
>>     I’d like to change the current filelock or introduce a new lock to
>>     oslo.concurrency.____
>>
>>     __ __
>>
>>     Proposed change:____
>>
>>     Add exclusive(write) locks for delete operations and shared(read)
>>     locks for create operations, to ensure that create from
>>     volume/snapshot____
>>
>>     can work on parallel and protect create operations from concurrent
>>     delete the source volume/snapshot.____
>>
>>     __ __
>>
>>     I’d like to get what’s your suggestions, thanks in advance.____
>>
>>     __ __
>>
>>     [1] https://blueprints.launchpad.net/cinder/+spec/enhance-locks____
>>
>>     __ __
>>
>>     __ __
>>
>>     -zhenguo____
>>
>>
>>
>> __________________________________________________________________________
>>     OpenStack Development Mailing List (not for usage questions)
>>     Unsubscribe:
>>     OpenStack-dev-request at lists.openstack.org?subject:unsubscribe
>>     <http://OpenStack-dev-request@lists.openstack.org?subject:unsubscribe
>> >
>>     http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>>
>> __________________________________________________________________________
>> OpenStack Development Mailing List (not for usage questions)
>> Unsubscribe:
>> OpenStack-dev-request at lists.openstack.org?subject:unsubscribe
>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>>
>
> __________________________________________________________________________
> OpenStack Development Mailing List (not for usage questions)
> Unsubscribe: OpenStack-dev-request at lists.openstack.org?subject:unsubscribe
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack-dev/attachments/20150627/09232d04/attachment.html>