nilfs and pohmelfs look seriously neat. I have two concerns though:
- nilfs is log-structured, which tends to be nearly pessimal for performance on rotating storage, as you rarely access files in exactly the same order as they were written. This problem is severe enough that it has torpedoed most log-structured filesystems in the past. How does nilfs avoid it?
- pohmelfs looked seriously neat as an NFS replacement (the performance figures are very impressive), but recent developments appear to be pushing it towards serving data from a memcached-like key->value store. This is very far from the NFS model ('a server with lots of stuff on it, we want to export that stuff without changing it on the server', so making a new local filesystem is out). I get the impression from Evgeniy's blog that the intent may be to allow pluggable backends, so that pohmelfs can serve its data *either* from a local fs or from a key->value store, but I have no idea if this is actually true (yet).
I guess I should damn well try it out and set up some pohmelfs-using systems myself. Anything that can outdo NFS (and is Unixlike: sorry, SMB) I'm in favour of.