Correct, it’s not safe … even if.
The emphasis on should support does not extend to how PMS locks the DB.
What results, which I’ve tested on NFS extensively, is a corrupt database.
PMS was not designed to be run in a distributed manner.
iSCSI should work fine because it is, as we know, a block device and handled differently than the network file sharing layer. I’ve not taken the time to prove that this works reliably because it’s rarely used. The performance hit is pretty bad when PMS is accessing the DB over any network … even a 10GbE link.
With iSCSI, all locking is handled within the local kernel block i/o driver.
The network simply connects to the remote storage.
With NFS, the remote NFS server is setting the advisory locks and that’s the key – the locks are not absolute.
Here are my results and instructions should you wish to pursue it using NFS
