So it looks like my planning to swap colon with a new machine with lots of disk (146GB of RAID1, to be precise) may not go ahead on the 7th to 8th as I'd been assuming. I'm not sure yet what, but this morning something caused both disks to stop spinning, and I saw the kernel log messages on the screen saying how the array had gone from OK -> interim recovery -> failed all within about 4s. Having just taken the better part of a day and a half to sync the current /export/home (~8GB), however, even finding some way of rebuilding it, and getting the disks to spin up worries me for that deadline. I'm currently not as confident in the hardware as I'd like to be - though it did survive with a reasonable uptime beforehand as munkyii.nodnol.org. Hopefully when I get back home, reseating everything will fix it - then what?
Update: It seems that the problem is with the RAID card (unplugging it and using the onboard RAID span the disks up fine). As well as this, there have been other little niggles with the card. This is a good thing, because I only just bought the card, and it is under warranty as a result.