NAS and backup power

I saw at www.raidtips.com an interesting post "Test your RAID" where it is recommended to pre-test fault tolerance.  One of the suggested approach to test fault tolerance is to do a simulated power failure.
However, just turning off the power is not enough to test an UPS. In normal operation NAS receives the notifications from its UPS unit continuously and takes action immediately. However, when starting up the reports concerning power failure are not received. On top of that one should consider that the entire cycle (from start up to shut down) may require up to ten minutes.

Let's consider such a situation:

1. suddenly power fails,
2. your NAS unit takes power from the battery for some time and then shuts down,
3. the grid power comes back and NAS begins to start up,
4. at this moment power fails again.

Now NAS is not able to process a report on power failure event until it fully starts up. As soon as Network Attached Storage loads, it detects that the power failure has occurred and starts to shut down.
But it may happen that the system will not be able to shut down correctly since UPS doesn't supply power long enough due to battery exhaustion (during the first cycle).
One can avoid this by setting the NAS up so that it finishes its work as soon as it receives a message that power failure occurs. Doing this one can save enough charge of battery for another start-stop cycle.
Also you can configure Network Attached Storage in such a way that NAS does not restart automatically, but manually after the power failure has occurred.