Do we have plan to separate create snapshot and backup snapshot? If that's true, only backup snapshot commands need to be synchronized since creating snapshot is fast.
-----Original Message----- From: Alena Prokharchyk [mailto:alena.prokharc...@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+improvement s+FS If you have any comments/suggestions/questions on the implementation, please let me know. -Alena.
