Topic: Advanced Power Management

[laurie_lewis]

I have done a search in the forum but I can find no help on this topic.

I have turned this feature on in the bios but the hard drives never spin down etc.  I am after a server that will not chew up my power but wake up on lan activities for me.

Any assistance greatly appreciated.

[calisun]

I have similar issue. I have also turned on power management in bios, but my hard drive never spins down. Is there something in SME server that I must turn on for power management to work? The issue is not so much power consumption, but premature hard drive failure if it keeps spinning all the time.
Another related question, my SME box is used as file server only, but even when all workstations are off, I still notice hard drive light blinks for less than a second every 10 seconds. Anybody knows what is cousing this?

[MSmith]

On the subject of disk power management for fileservers.  If you spin up the drive every time you want to access a file you will dramatically increase the latency of the file transfer ... not so good!  And my personal take on keeping hard drives spinning is that if they're spinning all the time they're in thermal equilibrium, not expanding or contracting, lubricants up to operating temperature, air cushion for heads maintained, etc.  Spinning the drives up-down-up-down-up-down IMHO is EXTRA wear and tear.  And you're not talking about a heck of a lot of power savings unless you've got a monster server farm!  Run a low-powered CPU, like a Pentium-M in place of a watt-hungry monster like a Pentium 4, and you'll save WAY more than you would powering down your hard drives.

[calisun]

I totally understand that continues spin up and spin down would be bad for the drive, that is why I set spin down to one hour in bios. So it would not spin down during the day as users are connected and it is being used, it would only spin down during the night when there is nobody connected. But it never spins down.
Drive that spins continuesly 24/7 would have shorter life span than a drive that spins 10/5.

[egerards]

In my SME box I have a second hard disk which I only use for backup purposes. Every night at 04:00 a rsync job copies /home and some other dirs to this hard disk. After this there is no need to continue to spin so I wanted this hard disk to spin down after 5 minutes of inactivity.

Indeed, power saving settings in the bios seem to be ignored, but fortunatelly there is a convenient tool called hdparm:

check current state of hard disk: hdparm -C /dev/hdb
set spin down time to 5 min (60 * 5 sec): hdparm -S 60 /dev/hdb
force to enter standby mode: hdparm -y /dev/hdb
force to enter sleep mode: hdparm -Y /dev/hdb

See the manual page for more details. If necessary substitute /dev/hdb with your device name.

If you include the 'hdparm -S ....' command in /etc/rc.local you will preserve the setting after a reboot.

[kruhm]

hdparm saves the day again.

i agree with msmith, maybe i'm missing something but i just don't see the point in doing this