It's pretty common to see advice to disable the write cache on individual disks used for databases because otherwise some disks will acknowledge writes that haven't yet made it to the disk surface.
This implies that some disks don't acknowledge writes until they've made it to the disk surface (Update: or that they report accurately when asked to flush the cache. Where can I find such disks, or where can I look for authoritative information on where to find such disks?
I'm setting up some DB servers that would really benefit from using write cacheing, but the application is price sensitive and I'd rather not double the cost of my disk subsystem for some caching RAID controller because I don't have enough information to know whether I can trust the cache in each drive.