After only running the server for a month or so, I already have my first disk failure. In fact, I think the disk failure wasn't even due to the heat of the last weeks, because I had problems with it from the start. Oh well, just sent it back today, 3 years guarantee no problem and the other two disks are still functioning ok. As soon as I have a replacement, I will submit each of the disks to a powermax test.
Luckily I have RAID otherwise I would have had a big problem.