Hi Indivision,
I haven't migrated my server yet to Freenas 11 on the Push side, and I am using my own replication script.
I am replicating to Freenas 11 on my backup PC and swap backup volumes.
Both my backup volumes are Write protected, so that Freenas doesn't mess with the data, except that replication is not being prevented. This has the benefit of guarenteeing datasets and snapshot will not be modified causing next snapshots to fail.
The issue with Read only volumes is that if you start replicating from scratch, or you created a new dataset that doesn't exist on the PULL side, having Read only volume will not prevent replication, however, when your reboot your PULL, or try to mount the dataset, Freenas will give you an error such as "Cannot mount dataset...".
It is scary at first, and you doubt your replication process and existance of your data as well as its integrity.
The good thing about ZFS is that your data is present and safe if the snapshot actually exist on the PULL.
If the dataset is not mountable, you will not be able to go into the folder location as it doesn't exist in memory.
If in doubt, you can do a diff of the snapshots or list the file content of the snapshots on the PULL but is pointless.
If the dataset cannot be mounted, because the volume is read only, you just need to go to CLI and change the flag as follow:
sudo zfs set readonly=off tank
Reboot your PULL server and Freenas will be able to mounted the remaining dataset.
You will be able to CD into the folders and list your files.
you can set volume as reado only after that:
sudo zfs set readonly=on tank
The key point to remember:
After replication, if the snapshot appears on the PULL, it means the files that exist on the PUSH that are pointed by this snapshot are also on the PULL.
There are also two types of replications, one which replicate the entire dataset permissions ( using the "I" option) or the one that will remove all permissions ( using the "i" option).