UPS Questions...

1. You need about a minute or two of runtime. Provided you're not overloading your UPS you should have this. I think it's generally recommended to not load the UPS with higher than a 80% load (if you put too much load on the UPS the battery will drain too quickly shortening its life, not to mention that you could overload your UPS by mistake)

2. Shutting down the NAS, I think takes less than a minute. Of course you should allow a bit of extra time just in case more is necessary.

3. If the NAS power cable is not both connected to a UPS and using UPS monitoring, then the NAS will shutdown unsafely which would be akin to holding in the power button till the NAS turns off to force a power off (not just initiating a power off, but bypassing the shutdown script and shutting down unsafely). This is not recommended. On the other hand,If the NAS's power is connected to the UPS and is using UPS monitoring then the NAS will shutdown safely when the shutdown threshold is met, which would effectively be pretty much like shutting down the NAS safely manually.

4. Connect the power cables for both units to the UPS. You can choose which NAS you use to monitor the UPS, but it would make sense to choose the Pro. You can use the network monitor feature, but do note you need to have the power for your router/switch connected to the UPS as well (routers and switches use little power and you can leave these to shutdown when the UPS battery runs out) so that the devices can communicate over your network when the power is out.

If you like you can even share the UPS with a PC. See Using the ReadyNAS to create a Network UPS for PCs

I know we approach the subject with varying degree of expertise, but option #3 sounds pretty rediculous. Unless I misunderstand, that seems like not using a UPS at all.

If either the power cable is not connected to the UPS or UPS monitoring is not used then you would have unsafe shutdowns. If just power cable is connected to UPS the NAS will shutdown unsafely when the UPS battery has drained. If just UPS monitoring then NAS would shutdown unsafely immediately when power failure occurs.

I have my NV, Pro 6 and UPS in a 'love triangle. ;)

I pulled the power on the NAS, and the directly connected Pro 6 notified the NV. So far, so good.

I managed to find another UPS for the network gear, so I only have the two NASes on the 750VA UPS.

So long as your second UPS keeps the network gear up longer than the first keeps the NAS units up that'll be fine.

Also be sure and test the UPS battery.
I have an APC that looked just fine to the readynas, fail when the power dropped.
It was good enough to stay down when the power came back up as I was not around at the time.
It took a while to fsck and resync the drives.
A new battery with higher amperage ratings will be periodically tested.
A Batteries Plus store is a good resource to have handy.

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