There are several commands need this kind of threshold, e.g. Move volume, create template from snapshot, So this is common requirement , not only for createsnapshot. Can we add threshold mechanism in host command queue to resolve this issue?
Anthony -----Original Message----- From: Edison Su [mailto:[email protected]] Sent: Thursday, October 11, 2012 4:42 PM To: [email protected] Subject: RE: FS on cloudStack createSnapshot synchronization improvement I only have one comment: Can we put this snapshot improvement code out of snapshotmanager? > -----Original Message----- > From: Alena Prokharchyk [mailto:[email protected]] > Sent: Tuesday, October 09, 2012 11:51 AM > To: [email protected] > 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+improv > e > ment > s+FS > > If you have any comments/suggestions/questions on the implementation, > please let me know. > > > -Alena.
