A bit of feedback on your post in regards to backup of FlexVol used for Openstack. Some of this may be obvious, but still needs to be described in the context.
Assume that you are using NFS as the protocol for the Netapp FlexVols that support the Cinder Backend(s). Let's discuss the Data Volumes that you mention first as VM's may require some more additional conversation. The Data Cinder Volumes could reside in either of the NFS FlexVols used by the Cinder Backends. There are some possibilities on how to use the Netapp Snap technology based on the application requirements for those "Data" volumes. Here are a couple of use cases:
Use Case #1 - The Data Volumes do not require any application consistent or application coordinated snpashots: One could have a snapsot schedule on the FlexVols with the proper retention, and use that as a potential mechanism for the backup for all cinder volumes within that FlexVol. There would be a prescribed series of steps to follow in order to execute a restore of that Cinder Volume as well.
Use Case #2 - The Data Volumes for an application require applicaiont consistent snapshots(think about MySQL, Oracle,etc). Then one would need to script or use the appropriate tool/product(ie SnapCreator) to quiesce the application, and take a NetApp Snapshot of the FlexVol containing the cinder Volume. There are a couple of things to think about as the FlexVol is a container for many Cinder Volumes. One would need considerations for the solution. Yet, you could still perform the appropriate restore of that specific Cinder Volume via the prescribed steps that would leverage the NetApp technology.
In regards to your questionabout SnapDrive - there is no integration between SnapDrive and OpenStack. One could use SDU if the host managing the Cinder Services was qualified on the IMT. But, you still would have similar concerns in regards to application consistent Snapshots. It's not providing an advantage over a product like SnapCreator in this type of use case(ie NFS).
Your other use of the Cinder Volumes for the VM's provides a bit of additional use. One would need to quiesce the VM, and then backup the FlexVol containing the Cinder Volume for the VM.
Overall, the restore of a Cinder Volume would require some specific steps to follow - mostly within the OpenStack context. We are working on some material around all of these types of questions now, and hope to have some material available or OpenStack on Netapp users soon. More in-depth use cases and answers will be forthcoming.