[CentOS] Being Green, Time to make the servers sleep!

Thu Mar 19 11:54:41 UTC 2009
Theo Band <theo.band at greenpeak.com>

James Bensley wrote:
> Shadies and Mentlemen;
> I am trying to be green and put our backup servers to sleep during the
> day and have them wake on LAN and fire back up at night for our
> nightly backups as "sleep" is a sort of low power usage mode.
> (At this point I would be curious to know the different levels of
> sleep, what can I achieve? Does my server just drop into a low power
> state, or can I stop the hard drives as well?)
> I am wondering if it is achievable to script the process of putting a
> server to sleep so I can cron tab its behind!
> I would assume it would be possible but I don't know how, does anyone
> have any idea?
You are probably best of putting your backup server on an already
running server as a virtual machine. If you really have only one server
running on your lan then you could also consider the following approach.
I use the power-on-time BIOS feature most MB have. My server start
itself every night at 01:55. It is then up and running just before
02:00. At 02:00 I schedule a cron job to do the backup. At the end of
the backup, the script just powers off the machine. The only thing to
experiment with is the time it takes to start the machine. Sometimes the
startup takes longer if disks need to be checked (ext3, every so may
boots) and the cron might not trigger. Using anacron is perhaps the
safest option in this case, but I did not experiment with that.
I could not use wake up on LAN, since the mirror is on a remote location
were it is really the only server.