Re: 2.6.18-rc2, problem to wake up spinned down drive?

From: Bill Davidsen
Date: Wed Aug 02 2006 - 12:50:23 EST

Tejun Heo wrote:
Harald Dunkel wrote:
Tejun Heo wrote:
Can you try the following instead of hdparm?

echo 1 > /sys/bus/scsi/devices/1:0:0:0/power/state

It will make libata involved in putting the disk to sleep and waking it
up, and, when waking, it will kick the drive in the ass by resetting the
channel. Please try with the latest -rc kernel.

Sorry to say, but this did not work:

# echo 1 > /sys/bus/scsi/devices/0:0:0:0/power/state
bash: echo: write error: Invalid argument
# ll !$
ll /sys/bus/scsi/devices/0:0:0:0/power/state
-rw-r--r-- 1 root root 0 Aug 1 20:00 /sys/bus/scsi/devices/0:0:0:0/power/state
# cat !$
cat /sys/bus/scsi/devices/0:0:0:0/power/state
# uname -a
Linux bugs 2.6.18-rc3 #2 PREEMPT Sun Jul 30 16:26:22 CEST 2006 i686 GNU/Linux

You probably should do 'echo -n 1', the parsing function is pretty picky.

Given that the data from the "cat" of state returned a zero with newline, perhaps unreasonably picky. On a Fedora kernel it just doesn't seem to work for SATA drives, sample size = 1.

Bill Davidsen <davidsen@xxxxxxx>
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