We are currently working on implementing a DR strategy. Instead of SAN-SAN replication, it has been decided to have 2 live file servers replicating via DFSR. However, I don't know whether or not this is a good idea.
Example: DFS does not replicate locked files. Let's say a user has a spreadsheet open for weeks. They do save periodically, but the file still remains open. Then, the active file server goes down and users are redirected to another server, where the file hasn't been replicated.
Is there a way to mitigate that scenario? Am I misunderstanding something? Or is DFSR not designed to be a DR technology?
Edit: What other deficiencies does DFSR have in a DR context, other than my example above?
I've just moved away from a DFS-R environment because of the very reason you described above. Locked files are impossible to deal with and causes all kinds of conflicts especially if both servers are being used like a proper failover (so users are hitting both servers at once).
To me, DFS-R is decent for replicating over WAN/VPN connections to remote offices and not as a DR solution. I highly advise getting some sort of shared storage and using Failover Clusters which have improved quite a bit in 2012 R2 (I'm still on 2008 R2, but it's served us well so far).
It is not designed for DR. Not in this way - in this case the user is the problem. I am not sure anything will handle that nicely.
DR also is a crappy scenario it will happily replicate a virus encrypting your files (or deleting them).
Yes and no, keep a delay between the sync to be sure to not sync a erase or a corruption. It's only a good way to keep file you don't want to loose, but it's a minimal "backup" scenario.
I would host that server in another location and on a local storage. (as I does not know your SAN topology)