On Sat, Jun 27, 2015 at 11:47 AM, Joshua Harlow <harlo...@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" <niuzhen...@huawei.com >> <mailto:niuzhen...@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-requ...@lists.openstack.org?subject:unsubscribe >> <http://openstack-dev-requ...@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-requ...@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-requ...@lists.openstack.org?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >
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