On Thu, 2005-08-25 at 16:54 +0200, V. T. Mueller wrote:
> @Marc: a battery-backed write cache is an optional hardware feature
> for the better controllers. This is somewhat paradox, because on
> important high-IO systems - which is where you usually use rather
> expensive RAID controllers - you rely completely upon UPS triggered
> shutdown routines in case of a power failure as long as your
> controller cache is not battery backed. It's quite tricky to restore
> a database that had just lost a couple of megabytes of transactions...
You still need to have write integrity down to the disks, since even
with big expensive UPS systems you still find some clown who manages
trigger the EPO (big red button that turns the power off - normally
carefully mounted in places where they can be hit accidentally), or
remove the power cable, or switch off the *wrong* machine.....
Never underestimate the resourcefulness of an idiot in a data centre.
Nigel.
--
[ Nigel Metheringham Nigel.Metheringham@??? ]
[ - Comments in this message are my own and not ITO opinion/policy - ]
