If anyone is using two SATA drives in their thecus n2100, I'd love to know what sort-of temperatures you are getting for your disks. Use smartctl in the smartmontools package and the following snippet to find out (the number in the last column): 

smartctl -d ata -A /dev/sda | grep -i temp

Use /dev/sdb for the second disk.

MY WDC4000KS drives are getting up to 60 degrees celcius, which is outside of the operating conditions for the drive :(

Come to think of it, I'd like to know what results you get with just one disk, too, and if you are employing anything extra to cool the device, above the one fan you get by default.

I'm Jon on irc.freenode.net or irc.oftc.net.