ReadyNAS Temperature?

may I post my temperature values here followed by some questions:
Disk1 (Hitachi 1862GB): 51C/123F
Disk2 (Hitachi 1862GB): 54C/129F
Disk3 (Samsung 931GB): 47C/116F
Disk4 (Samsung 931GB): 40C/104F
Fan (Noctua NF-B9): 1875rpm
Temp1: 44C/111F

Before I installed the Noctua-Fan (2 days ago) I had more or less the same values with the original fan (but double speed and triple noise).

Since a few months I get warning E-Mails because of Disk2 (high temperature) - it reaches 55C/131F to 56C/132F. Wouldn't it be a good feature for next Raidiator-Version to set the lowest temperature value which causes the system to send warning E-Mails? If I could set the minimum temperature to 57C/133F I'd never get an E-Mail and the temperature would be still ok, I think.

Are the temperatures still ok? My NAS is located at a quite hot place (in summer exceeds 30C), therefore the temperatures may rise a bit higher than usual....?

In the future I will try to buy disks which don't get too hot. Can anybody make a brand comparism (two different disks of same size in the same cabinet) or do you know which disks are known for not getting too hot?

At which temperature does the NAS switch off if this option is checked?

thank you everybody!
regards joe

wow.... I didn't expect that:

with the panel open and 10 minutes later:
Disk 1: 46C
Disk 2: 48C
Disk 3: 42C
Disk 4: 35C
Temp 1: 40C

.. simple answer for hot days