[TAG] 2 cent tip

[John Karns]

Many of us have resorted to backing up our systems to hard disks in the
last few years since increases in hard disk storage capacities have left
those of affordable removable media behind.  My solution has been to add
two archive volumes on IDE drives of 40 GB and 80 GB.  But since they
serve as archive volumes rather than system volumes, it seemed a good idea
to set them up so that they wouldn't spin all the time since the system
runs 7 x 24.  The IDE driver accomodates this with a parameter which can
be set via the utility hdparm.  By placing a command such as 

hdparm -S 240

in a system start-up script (look for them in /etc/init.d), the drive will
spin down after 20 minutes of inactivity on the drive.  Results my depend
on the filesystem on the volumes, but with reiserfs, I can mount the
drives and have them spin up on demand, which is automatic by just reading
from or writing to the volume.  The idea is that with the drive spun down
most of the time, it's like having off-line storage from the stand point
of avoiding ware and tear on the hardware, but with the advantage that the
volume(s) are readily available when needed.

The format of the -S option (hdparm -S n where n is a value between 1 and
255) accomodates settings between 5 seconds and 5.5 hours, according to
the following scheme:

Values         Time
---            ----
  1 - 240    5 sec to 20 min, increments of 5 sec
241 - 251   30 min to 5.5 hrs,increments of 30 min 

252         21 min
253         "vendor defined"
255         21 min + 15 sec