Best Practice for cloning/copying/moving data from one zvol to another

[Darren McGrandle]

I have an interesting problem and I'm not sure how to solve it. I am using the Cinder driver to create zvols on a FreeNAS system and it's working great. Now, however, I need to migrate OpenStack to another system. I don't want to have to re-create all of the virtual machines and manually copy the data if I can get away with it. The boot and data volumes for all the VMs exist as zvols on my FreeNAS system. However, because of the way OpenStack works, for a volume to be recognized it has to be created within the OpenStack environment. This creates it on the FreeNAS system with a random name.

What I would like to be able to do is create a new zvol within the new OpenStack environment on the same FreeNAS system as the current zvol that contains the VM's data. Then I would like to use the FreeNAS GUI (or command line) to essentially snapshot-restore (or use some similar method) to move an exact copy of the same data from the old zvol into the new one that was just created. Wiping out the existing data in the new zvol is fine.

What is the best way to go about this? Currently running FreeNAS-11.3-U5

Thanks for any help,
:D

 

[fidgety]

You can use zfs send and zfs receive with a local pipe on the same server. In other words, replication doesn't have to be over a network.
There is an example at https://www.howtoforge.com/tutorial/how-to-use-snapshots-clones-and-replication-in-zfs-on-linux/

Hope that helps,