I was doing some testing earlier this week on a KVM cluster, and noticed that when using S3 for secondary storage snapshots on RBD primary storage take a lot longer than they do with NFS primary storage.
I think this is due to the NFS snapshots being output/uploaded in QCOW2 format, while RBD snapshots are output in RAW format. It appears that even when using sparse RAW files they are uploaded to S3 with the 'allocated' size instead of the sparse size. My question is: Is there a good reason for RBD snapshots to be output as RAW instead of QCOW2? It appears that QCOW2 templates are automatically converted when deploying them as RBD, so that shouldn't be a problem. The only downside I can think of would be having to convert the RAW RBD data to QCOW2 as an extra step when creating snapshots, but even that seems like it would take less time than uploading the RAW images to S3. Thoughts? Thank You, Logan Barfield Tranquil Hosting
