[ltp] Hard disk ignoring hdparm? (Not spinning down)

[Christoph Singer]

I have a Thinkpad R40 with a 40GB Travelstar HD (IC25N040ATMR04).
I'm running SuSE 9.1 in laptop_mode, i.e. file system commits to the 
hard disk are set to be only every 10 minutes.

Yesterday I noticed that my hard drive was spinning down immediately 
after every disk access (and hdparm -C reported "standby"). I played 
around with hdparm and noticed that this occured for all hdparm -B 
values from 1 to 127, no matter which -S value was set. hdparm -B 128 
and above caused the drive to spin down only after the time interval 
specified by -S.

Well, and now my surprise: today the drive does not spin down at all, no 
matter what -B and -S options I set. I changed nothing in my 
configuration, there are no other services running. The only thing I did 
was rebooting to Windows XP in the meantime.

I really don't know what to do - I can set "hdparm -B 1 -S 1", but the 
drive never goes to standby mode (and hdparm -C always reports 
"active/idle"). hdparm -I reports the right APM setting ("Advanced power 
management level: 1 (0x1)") after setting hdparm -B 1, and with this 
value the drive yesterday span down immediately.

I'm quite sure that no process is accessing the disk, because if I do a 
hdparm -y the drives spins down and remains in standby mode for some 
minutes. But the -B and -S values have no effect at all.

It's quite mysterious. Any ideas what may have happened, and how can I 
set the disk to standby mode?

Christoph