Thanks Brian, that's a good point.

In this case the case fans are running constant speed and only the cpu  
fan is PWM controlled. So the temperature over the drives should have  
been more or less OK.

Unfortunately the BIOS on this Intel motherboard didn't show fan speed  
or temperatures as it probably should so there was no alarms going off.

On another note, I took the failed drive I replaced in my array  
(/dev/sdh) and put it in another machine (win7) and run Western  
Digital's diagnosis software and it says the drive is OK.

I'm wondering if perhaps it's possible the CPU has been running too  
hot and the raid array failed because of that.

Anyway, I'm still at loss what to do and what my next step should be...

Thanks,
Peter



Quoting Brian Candler [off-list ref]:

On 14/10/2013 17:31, peter@steinhoff.se wrote:

quoted

I found that the CPU fan had stopped working and replaced it. The  
case have several fans and the heatsink seemed cool even without  
the fan (it's an i3-530 that does nothing more than samba so it's  
mostly idle). Possibly the hardrives has been running hotter than  
normal for a while though.

Aside: in some cases it might be a good idea to disable the case  
control - in the BIOS if your system supports it, or by removing the  
fan control header completely.

This was a system with 24 drives and 3 LSI HBAs. The case fan  
control was based on the CPU temperature alone. Therefore if the CPU  
was idle, the fan speed went very low, which meant that the drives  
and the HBAs got very hot.

This led to the perverse situation that when I was testing the  
system heavily with lots of reads and writes it went for weeks  
without problems, but if I left it idle for a day or two the HBAs  
crashed!

Regards,

Brian.