Quote:

I could of course just drop back to a simple mirror and forget RAID5, but I really want that extra 250Gb.


Yeah, I know the feeling.

A *lot* of people seem to prefer RAID 1+0 with a four drive setup.
That's two pairs of RAID1, which are then combined into a single virtual drive
with RAID0 striping across the two pairs. Or the other way around (0+1)

Very reliable, very fast -- more so than just two pairs of RAID1 would be.
But still no extra 250GB.

Cheers