I'm a
sysadmin who unfortunately works with these things every day...
Yes, the intent is failover. You plug both in, and if one fails, the
other carries the unit. IIRC, your unit will make an annoying
beeping sound if one of the power supplies goes south.
I'm sure I can workaround the alarm -- add a jumper between the sense
inputs (on the "environmental board") for the two power supplies.
Actually, check on the back of the unit -- unless I'm thinking of the
wrong unit, there should be a pushbutton to cancel the alarm.