some days ago I discovered (using Munin) that my server had high iowait times. The reason was that write cache was disabled. I enabled it using hdparm -W1 /dev/sda but after some time (ramdonly) it got disable again.
No information about this event in system logs. I updated kernel to 2.6.18-308.20.1.el5 #1 SMP, it seems to be better but the problem continues.
I turned off every service but problem still continues.
Do you know where can I get some information or log to know why write cache turns off?
Some hardware information:
Hard drive: Western Digital WDC WD5000AAKX-00ERMA0 Mother Board: Intel D945GCPE
Any help is appreciated.