CloudStack currently snapshots vm disks by taking hypervisor snapshots. However, when implementing the storage subsystem API interface takeSnapshot(), the VM associated with the requested volume is not quiesced since a hypervisor snapshot is not necessarily taken. When creating a storage level snapshot, there are ways around this and 'quiescing' the vm without actually quiescing it (through hypervisor APIs). I would like to propose that there be an option to quiesce VMs when taking snapshots both manually and through recurring snapshot policies. One issue I see with this is that this option is not always applicable. If the default storage provider is used, a hypervisor snapshot will be taken and therefore the VM will always be quiesced. Some storage providers may not respect the user's request to quiesce. Because of this, I suggest that the option be shown to the user as 'Quiesce VM (if applicable)'. This indicates to the user that the option will be passed to the management server and respected if possible.
I will work on formalizing a full functional spec if needed but wanted to get this up for discussion ASAP. I have created a JIRA ticket: https://issues.apache.org/jira/browse/CLOUDSTACK-4774 Thanks, Chris -- Chris Suich chris.su...@netapp.com<mailto:chris.su...@netapp.com> NetApp Software Engineer Data Center Platforms – Cloud Solutions Citrix, Cisco & Red Hat
