The reallocated sector count is up on that hard drive, so it may well be failing.
I had best work on how to boot the machine if is dead. BIOS might handle that, or GRUB on a floppy or CD ought to work.
My BIOS indeed lets me boot off of my second hard disk instead of the primary. GRUB2 thinks, then, that the secondary disk is disk 0 and the primary disk 1, reverse to the normal, but then Linux thinks the drives are as always. It uses letters a and b instead of a number, but that’s just details.
I have no idea how Windows addresses multiple drives. (The letters C:, D:, etc., refer to filesystems, not drives.) My guess is it would do the same as GRUB, and that they are getting the switchover from the BIOS; and I would guess that the Linux kernel accesses the hardware directly and so has no idea that the drives are flipped in any sense. It just knows how the hardware is set up.
My handwritten GRUB2 configuration sure is faster than the one generated automagically by Ubuntu, or at least I think this is the reason for the speed increase. I think the automagical settings could be tuned for speed, however; the default seems designed for removable drives showing up who-knows-where and having to be found by asking them all for their ‘identification papers’.
Seems Amazon sells the terabyte hard drive I have for $79.99 and is eligible for Amazon Prime shipping. (We be member family.) So I can just go buy another of the same, if I run into warrantee problems or inconveniences. (One might have to let the drive fail its self-test, for instance, whereas I, being obsessive-compulsive and wishing to stop thinking about it, might choose not to wait.)
Hard disks must have practically no profit margin. And BTW Kristy tells me Sony says they will quit making floppy disks. (I’ve got a bunch of their’s, already. Good disks.)