ReadyNAS 1500 - when is a dead disk, dead?

[fizzy]

I've got conflicting indicators of a disk status on our readynas1500 4 bay unit.

All 4 disk leds are solid green on the front panel of the unit.
Raidar (4.2.27) shows 4 solid green disk indicators.
FrontView: Status > Health > Disk 4 = Dead
Capacity showing as 2769gb with 4 x 1tb drives

So how do I tell if disk 4 is actually dead?

[StephenB]

Probably the safest thing to do is remove it and test it in a PC with vendor diagnostics (seatools for seagate, lifeguard for western digital).

I'd also look at the SMART stats in Frontview.