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From Alena Prokharchyk <Alena.Prokharc...@citrix.com>
Subject Re: FS on cloudStack createSnapshot synchronization improvement
Date Fri, 12 Oct 2012 00:58:31 GMT
Its out of the snapshotManager. Synchronization is being controlled by the
code SyncQueueManagerImpl. Number of entries the object-we-sync-on (HOST)
can handle, is being passed to the syncQueueManagerImpl when we
createSnapshot async job is submitted.

I did just one change in the SnapshotManager - extracted the method from
existing code. The method returns the destination host where the
createSnapshot command will be sent to.

-Alena.

On 10/11/12 4:41 PM, "Edison Su" <Edison.su@citrix.com> wrote:

>I only have one comment:
>  Can we put this snapshot improvement code out of snapshotmanager?
>
>> -----Original Message-----
>> From: Alena Prokharchyk [mailto:Alena.Prokharchyk@citrix.com]
>> Sent: Tuesday, October 09, 2012 11:51 AM
>> To: cloudstack-dev@incubator.apache.org
>> Subject: FS on cloudStack createSnapshot synchronization improvement
>> 
>> Hi All,
>> 
>> I'm planning to introduce some changes to create snapshot behavior for
>> the
>> future cloudStack release (the changes will go to asf/master branch).
>> The
>> fix is fixing the problem described below:
>> 
>> "With  the current code for snapshots, cloudStack always creates
>> snapshot
>> on  the host where vm is Running (for vms in Running state) or on the
>> host
>>  where vm used to run the last time (for vms in Stopped state). As the
>> createSnapshot commands are not synchronized on the agent side, the
>> case
>> when multiple  commands are send to the backend at the same time can
>> lead
>> to the  performance issues on the hypervisor side.  At the end there is
>> a
>> high  possibility that createSnapshot command might time out on the Xen
>> side.
>> The  solution is to synchronize number of concurrent snapshots per host
>> basis. The threshold should be configurable as the customer usually
>> knows
>> how many snapshots at a time the backend can handle.
>> While the  concurrent snapshots are being processed by the backend, all
>> subsequent  snapshot commands scheduled for execution on the same host,
>> should wait  in the queue"
>> 
>> 
>> Here is the feature FS available for the review:
>> 
>> https://cwiki.apache.org/confluence/display/CLOUDSTACK/Snapshot+improve
>> ment
>> s+FS
>> 
>> If you have any comments/suggestions/questions on the implementation,
>> please let me know.
>> 
>> 
>> -Alena.
>
>



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