APM

[Chuck Swiger]

Hi--

On Nov 13, 2009, at 12:15 PM, James Phillips wrote:
> I initially set the time-out to 60 seconds, then 300 seconds in a  
> vain attempt to see the actual power savings. With a 900 second time- 
> out, the drive only spun down once in the past 12 hours.
>
> It appears that syslogd can defer *one* log entry. Understandable,  
> since you don't want to loose too many logs in a power failure.

One of the first things you should consider is either disabling  
syslogd entirely, or else setup logging to a RAMdisk (ie, have an  
initial copy of what's in /var on the hard disk, setup a RAMdisk and  
mount as /var, then copy over the /var tree from hard drive to RAMdisk  
during early stages of system boot).  The advice given for NanoBSD or  
embedded NetBSD systems about conserving writes to a flash-based  
filesystem would be helpful in your case.

You might also want to note that 2.5" laptop drives are/should be  
explicitly designed to spin down and park themselves much more often  
than generic IDE drives are; some generic desktop drives will fail  
quite rapidly (ie, in a matter of months) if you attempt to spin them  
down many times a day.

You might also give some consideration to trying a Mac Mini with  
maximum power-savings mode enabled; OSX provides significant amounts  
of hysteresis to avoid spinning the disks up and down, and will buffer  
significant amounts of data being changed into RAM to coalesce  
filesystem activity into fewer periods of disk activity.

Regards,
-- 
-Chuck