Thanks for the link. In that post, he writes "Note: when we talk about disk controller we actually mean the caching performed by the controller or the disk itself. In environments where durability is important system administrators usually disable this layer of caching." I'm not sure I completely understand that note. Can you illuminate?
That's probably in cases where the disk controller can't guarantee that accepted writes will make it to the disk in the case of power failure. I worked with bare metal servers that had redundant power supplies including to the caching/raid disk controller and disks that in the event of power loss could still guarantee that writes that were 'sync'd by software were written after power loss.
