Folks, I've just been through a "replace a disk" scenario that went wrong. It *isn't* a "disaster", because the machine wasn't being used for anything interesting at the time. I am recounting it here in case others can benefit (and so you can all smirk at my expense :-).
Old NetApp F220. One disk died. Called support guys; they sent another disk. Typed 'disk swap', swapped a disk, typed 'disk unswap'.
Hmmm. One thing wrong, another possibly. I'd swapped the wrong disk (counted them from the wrong end), and I'd possibly taken too long to complete the swap. All I know is, the filer went down in a blaze of glory.
When I rebooted, it failed to load the OS; error "Invalid opcode" (i.e. it read junk off the disk).
So I rebooted from floppies (after swapping the disks back around correctly), and that seemed cool -- it figured out which disk was what, and did all the necessary RAID reconstruction. Everything looked OK.
Rebooted. Failed to load the OS: 'Invalid opcode' again. Hmmm... At this point, I said, "Never mind" and just rebuilt the whole thing from scratch.
What I *think* I could've done was: reboot from floppies; splat the ontap stuff into /vol/vol0/etc from afar; typed 'download' at the filer, and it might've worked. (But would I have had reason to trust any of the ordinary RAID data at this point?)
If you spot a place where I (+ support guy) went badly wrong, other than what I've outlined, I'd like to know. Thx,
Will