HDD power down (Re: [plug] cdrom not ejecting)

[Daniel Foote]

> Just a note... Never, I repeat, NEVER do this to a mounted partition,
> that contains your kernel, or system binaries... It just might not
> recover properly ;-)
> Of course, an unmounted drive is fine!

I've done it before on a mounted system drive. It worked ok... the
disk would wake up again upon access. But doing a few cycles of this
caused the machine to lock up...

If you want automatic sleeping mode, use /hdparm -S. From the man page:

       -S     Set  the  standby  (spindown) timeout for the drive.  This
              value is used by the drive to determine how long  to  wait
              (with  no  disk  activity)  before turning off the spindle
              motor to save power.  Under such circumstances, the  drive
              may  take as long as 30 seconds to respond to a subsequent
              disk access, though most drives  are  much  quicker.   The
              encoding  of  the  timeout  value is somewhat peculiar.  A
              value of zero means "timeouts are  disabled":  the  device
              will  not automatically enter standby mode.  Values from 1
              to 240 specify multiples of 5 seconds,  yielding  timeouts
              from  5  seconds  to  20  minutes.  Values from 241 to 251
              specify from 1 to 11 units of 30 minutes,  yielding  time-
              outs  from 30 minutes to 5.5 hours.  A value of 252 signi-
              fies a timeout of 21 minutes. A value of 253 sets  a  ven-
              dor-defined timeout period between 8 and 12 hours, and the
              value 254 is reserved.  255 is interpreted as  21  minutes
              plus  15  seconds.   Note  that some older drives may have
              very different interpretations of these values.

I use this on my fileserver... 3 out of the four disks are set to
sleep after 30 minutes of no activity. The wakeup delay is annoying,
but the disks only spend an average of 1-2 hours a day running at most
- saving a fair bit of power (0.9W spun down, 7.3W spun up and idle...
ok, it's not that much, but over 3 disks...).

Anyway, now I'm straying off topic.

Have fun...

Daniel Foote.