>Write caching is a technology that's been around for a long time. It's well understood and has been reliably implemented in thousands of different configurations. Turning it off can result in a large performance hit and should never be undertaken lightly.<

It's not "write caching" that is the problem per se; it's the "I/O complete" notification.

Apparently, there were/are some controllers that would notify the O/S that "I/O is complete", when in fact it wasn't; they would post the notification and then do the writing ("write-behind", I think it's called). A problem could arise now if the controller (or something) crashed and there was no battery backup; the "system" assumes the data was written, when in fact it wasn't and there is no way to recover. Or ... one could "reset" the controller, which would dump the cach, possibly AFTER a notification was sent but before the write.

In any event, turning of write-caching (with SQL Server) "might" not make a "big" difference (5% at 250 I/O per sec).

One controller that supposedly can handle the above issues is the "Compaq SMART-2" (whatever that is).