Okay, it was all my own stupid fault.
I've not had to set up any disks on NL for a while and the big red scary warning screen about potential loss of data in the event of a power failure was enough to convince me that turning of write caching was the right thing to do. Not so. Caching is back on and everything is fine again.
The experience did make me take a look on ebay for a battery backup unit for the 9500S-4LP but I could not find one. Does anybody have any ideas about where else might be worth a look?
Ray they do keep popping up from time to time.
Another way might be to have a UPS for the box which will protect it for a short time (a 2Kw one should give about an hour or so ) so that would definately protect for short brown outs/fluctuations. It all depends on how much you write to the box and for how long in a session and also how often?
If you are only writing manually you can stop it if you get a power cut but also if your source machine isnt on a UPS then you dont really have a problem as that will stop writing and as long as the NL box is on a ups (No matter what size) it should last long enough to clear out the 128/256 mb of cache.
Does this maybe give you some ideas.