What is Snapshotting an Azure Drive:

  • Snapshotting is a quick and efficient way to perform a backup of your drives
  • This is usually used to create a snapshot of a drive to allow execution to continue from that snapshot at some point in the future.
  • This could be used to roll back execution to that prior version or to potentially share the state of the drive with some other application instances.

 

Azure Drive Snapshots provides:

  • A way of sharing drive data among Windows Azure application instances.
  • The snapshot drive can be copied to another Page Blob name for another application instance to use as a read/writeable drive.
  • Snapshots blobs can be mounted as read only drives, and a single snapshot can be mounted as a read-only drive by many VMs at the same time.

 

Updating Azure Drive along with Snapshots:

  • When you have a Windows Azure Drive mounted, all writes go directly to durable storage. So If VM which is using Cloud Drive snapshot is restarted by any reason, you would lose only that data which hasn’t yet been flushed to disk by the operating system. The flush operation is handled by the guest OS file system driver. The drive cache which you have used for mounting drive is only for reads so it will not impact to file write process.
  • So if you have an Azure Drive that is using snapshot data and is shared by several worker roles, how u can update the data on this Azure drive. You must know that when you take a snapshot, that snapshot never changes. You can mount that read-only by a bunch of VMs, and they’ll all see the data from the time of the snapshot forever.
  • Updating snapshots drive and then taking new snapshot will be considered a new drive/blob. So if you want to use updated snapshot you can you can have the read-only instances unmounts the snapshot they have mounted and mount the new one. Snapshotting is like copying the VHD as it currently stands into a new file.

 

Read more about Azure Drive at: