[ILUG] Why RAID

[John P. Looney]

On Thu, Jul 15, 2004 at 08:40:12AM +0100, Niall O Broin mentioned:
> The Netapp WAFL is another different thing, though a very wonderful thing, it
> must be said, if your budget runs to it. AIUI this does allow exactly what
> Gareth described - when you need more space on a filesystem, you just plug in
> an extra disk, and this space automagically becomes available, and RAID
> protected. This definitely counts as "sufficiently advanced technology" in my
> book :-) The curious can find papers by Netapp people describing this - I
> really must read them in detail one day.

 It's not that magic; it's just RAID4. When you keep parity on just one
disk, it's reasonably easy to just keep adding new disks, as long as the
parity disk has sufficent storage. Of course, as the parity disk gets
written to all the time, it has to be a lot faster.

John