Disk 28 failed. It was a Seagate drive and we repaced it with the same model. It appears to need to have the Netapp Firmware installed, but when I try I get a "Firmware is up-to-date on all disks" message. The disk status shows as broken, and it's not in the spare pool, so I can't zero it or add it to a volume. I've given my sysconfig -v below. Note that we no longer have a support agreement with Netapp as this device is to be retired anyway, so I can't download the latest software. I just need to get the spare going again. Much thanks!!!
I'm afraid the answer is you need to have a disk sourced from NetApp for it to work (as there's custom NetApp firmware there you can't get elsewhere). The FAS250 is still supported so you might be able to do a support renewal. Alternately, I might check with a place like ZeroWait (zerowait.com -- no experience using them so buyer beware).