[OmniOS-discuss] illumos power management

[Paul B. Henson]

I think the storage server I'm working on at home (current omnios stable) is
spinning down disks; whenever I get back to it after not touching it for a
while, anything touching my export pool (dual 6 x 3TB WD Red RAIDZ2) takes a
long time to respond, and then goes back to normal.

My current power.conf is:

-----
autopm                  enable
autoS3                  disable

cpupm                   enable
cpu_deep_idle           enable
cpu-threshold           1s
-----

I had thought that when running on server class hardware the default was not
to spin down drives, but perhaps I was mistaken? Hmm, or maybe the default
is to just skip power management completely, and explicitly turning it on
turned on everything. 

I'm thinking about adding "system-threshold always-on" to the configuration,
which I guess will disable all power down functionality, other than CPU,
which is controlled by the "cpu-threshold" parameter? What other power
savings would this turnoff? I am in general in favor of saving energy :),
other than for the disks, as the latency is too high and causes too much of
a delay, and it's not clear if setting the system-threshold to stop spinning
down disks will also disable other potentially desirable power savings. I
guess the other option would be to explicitly configure device-thresholds
for all of the disks individually. Is there any way to list what components
of a system support power management?

While on the subject, any thoughts on event-mode vs poll-mode for cpupm?
It's not clear from the man page what the default is if you just set it to
"enable".

Thanks.