Is it better to power off NAS the hours I'm not using it?

I don't think the disk failures are directly related to the power-off. The NAS does a volume scan when it boots, and I suspect that the volume scan is simply uncovering the disk failure.

If you don't have a backup, it would be a good idea to create one now (while you are waiting for the WDC Red to arrive).

To your main question - assuming you have a regular schedule, I don't think it matters if you use the timer or manually turn the system on/off. The practical advantage of the timer is that you won't forget.

StephenB wrote:
I don't think the disk failures are directly related to the power-off. The NAS does a volume scan when it boots, and I suspect that the volume scan is simply uncovering the disk failure.

That's what I think too.

StephenB wrote:
If you don't have a backup, it would be a good idea to create one now (while you are waiting for the WDC Red to arrive).

I've only got about 550gb left so it's not enough. Any ideas on this?

StephenB wrote:
To your main question - assuming you have a regular schedule, I don't think it matters if you use the timer or manually turn the system on/off. The practical advantage of the timer is that you won't forget.

I mainly do this for power consumption and HD life extension. (a bit late now though :P )

Leaving the NAS on, with a conservative disk spindown setting is another approach. The NAS itself doesn't draw much power, and if you aren't using it during the day you will get additional power savings. Perhaps a 30 minute threshold - you don't want the disks to be spinning up frequently. I'm not sure how any of these options this actually effect HD life. Spinning the drives up creates more stress than keeping them spinning, so there is a trade-off here. However, the options do save power.

On the backup, of course you could attempt to save "critical" data on the space that you do have. Or get another USB drive.