<div dir="ltr"><div class="gmail_default" style="font-family:monospace,monospace"><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Jun 27, 2015 at 11:47 AM, Joshua Harlow <span dir="ltr"><<a href="mailto:harlowja@outlook.com" target="_blank">harlowja@outlook.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">Duncan Thomas wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
We are working on some sort of distributed replacement for the locks in<br>
cinder, since file locks are limiting our ability to do HA. I'm afraid<br>
you're unlikely to get any traction until that work is done.<br>
<br>
I also have a concern that some backend do not handle load well, and so<br>
benefit from the current serialisation. It might be necessary to push<br>
this lock down into the driver and allow each driver to choose it's<br>
locking model for snapshots.<br>
</blockquote>
<br></span>
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 ( <a href="https://www.youtube.com/watch?v=xnWKz7Cthkk" rel="noreferrer" target="_blank">https://www.youtube.com/watch?v=xnWKz7Cthkk</a> ) 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).<br>
<br>
Also I'd expect/think operators would rather prefer a toyota at this stage of openstack :) Ok enough analogies, ha.<br></blockquote><div><br></div><div><div class="gmail_default" style="font-family:monospace,monospace;display:inline">Well said Josh, I guess I've been going about this all wrong by not using the analogies :)</div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
-Josh<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">
<br>
On 27 Jun 2015 06:18, "niuzhenguo" <<a href="mailto:niuzhenguo@huawei.com" target="_blank">niuzhenguo@huawei.com</a><br></span>
<mailto:<a href="mailto:niuzhenguo@huawei.com" target="_blank">niuzhenguo@huawei.com</a>>> wrote:<br>
<br>
Hi folks,____<br>
<br>
__ __<span class=""><br>
<br>
Currently we use a lockfile to protect the create operations from<br></span>
concurrent delete the source volume/snapshot, we use exclusive____<br>
<br>
locks on both delete and create sides which will ensure that:____<br>
<br>
__ __<br>
<br>
__1.__If a create of VolA from snap/VolB is in progress, any delete<br>
requests for snap/VolB will wait until the create is complete.____<br>
<br>
__2.__If a delete of snap/VolA is in progress, any create from<br>
snap/VolA will wait until snap/VolA delete is complte.____<br>
<br>
__ __<br>
<br>
but, the exclusive locks will also result in:____<br>
<br>
__ __<br>
<br>
__3.__If a create of VolA from snap/VolB is inprogress, any other<span class=""><br>
create requests from snap/VolB will wait until the create is<br></span>
complete. ____<br>
<br>
__ __<span class=""><br>
<br>
So the create operations from same volume/snapshot can not process<br></span>
on parallel, please reference bp [1].____<span class=""><br>
<br>
I’d like to change the current filelock or introduce a new lock to<br></span>
oslo.concurrency.____<br>
<br>
__ __<br>
<br>
Proposed change:____<span class=""><br>
<br>
Add exclusive(write) locks for delete operations and shared(read)<br>
locks for create operations, to ensure that create from<br></span>
volume/snapshot____<span class=""><br>
<br>
can work on parallel and protect create operations from concurrent<br></span>
delete the source volume/snapshot.____<br>
<br>
__ __<br>
<br>
I’d like to get what’s your suggestions, thanks in advance.____<br>
<br>
__ __<br>
<br>
[1] <a href="https://blueprints.launchpad.net/cinder/+spec/enhance-locks____" rel="noreferrer" target="_blank">https://blueprints.launchpad.net/cinder/+spec/enhance-locks____</a><br>
<br>
__ __<br>
<br>
__ __<br>
<br>
-zhenguo____<span class=""><br>
<br>
<br>
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