># I suppose ideally, on modern machines especially, all individual disks
># should be mirrored, especially for root and swap partitions, and all
># other file systems should be at least mirrored, if not RAID-5.
>
>I don't understand mirroring swap.  I guess I'm stupid.  Please, enlighten
>me.

Support a simple dedicated system:

1 drive holds the whole system (root, swap, extra data partitions, etc).

Now you put a 2nd drive onto to mirror the first and provide redudancy.

If you don't do swap in that case, you lose. When a disk dies, you lose a
swap partition and anything which has paged out to it now loses. If you mirror
swap across both you can lose a drive and keep up and running. As as matter of
fact if you don't do swap in that case you might as well not mirror at all
since it's kinda unlikely you'll have a localized outage only on a drive...
(it has happened to me, but it's a lot more rare to see)

James