To summarize the underlying problem, babylon5's Linux install is ancient and clogged with cruft, and its SCSI hard disks are dying rapidly.
Simple solution: Install an inexpensive SATA controller and a new mirrored pair of SATA disks.
Well, by swapping controllers around so that the existing SCSI disks aren't the first devices, I can get the machine — which is built on an Asus A7V333 motherboard — to boot from a SCSI CDROM which it will not, as a general matter of course, condescend to boot from. From that CDROM I can boot a Gentoo liveCD, set up the new disk, install Gentoo, build a kernel, set up grub, etc, etc, etc, all with relatively little issue (aside from the part where I typo'd "-mtune=athlon-xp" as "-mtune=athlonxp" which resulted in gcc declining to compile anything).
There's just one problem. Try as I might, this motherboard WILL NOT boot from SATA. Leaving me squarely behind the eight ball for upgrading the machine, I think, unless I hold my nose and suffer with PATA. It'd be cheaper to buy a new motherboard, CPU and RAM than to buy a pair of new SCSI disks.
(Update 2355: I didn't even have much luck with PATA so far. I even tried dropping in my one good spare PATA disk, an 80GB Seagate Barracuda of uncertain age, just to put a bootloader on its MBR to boot the SATA disk. No joy; grub would install but wouldn't load.)
