loss of array after drive failure; problems with ST3500320AS

Sadly, a purchase 4+ years ago was covered only by a 3-year warranty (Netgear was good, however, about an out-of-warranty replacement of a power supply, apparently a known problem at the time the unit was bought).

I did not replace any drive with the system running. I did force a shutdown, then restarted it with drive 3 removed, and got a "Checking FS" message in the LED and a stalled system. So I powered down, replaced drive 3 and removed drive 1, and then powered it up again. It then booked, went out and found the UPS and the two attached USB drives, but reported as to "Drive C: 0/0MB Free". I don't know whether it tries to write to the drives during bootstrap, but if it doesn't I would have thought the drive data were intact. And it is puzzling to me that the one drive that has remained in the system (drive 2) is now reported as empty.

I do not religiously monitor the SMART data, but the last time I looked, probably several weeks ago, there were no reported errors or reallocated sectors on any drive. And the drive in question had been in the machine for only about four months (and is still under its Seagate warranty), so it does seem to me that the NV+ does not play particularly well with this particular drive, though it is on the HCL. And I thought the machine was supposed to generate alerts if drive errors begin to mount.

Thanks for the thoughts. I may try opening a support ticket if I do not get help in the forum.