FreeNAS doesn't recognize C3-state on ProLiant

[RBMaurice]

Hi guys,

I've been testing and playing with FreeNAS for some weeks now on my HP ProLiant ML310e Gen 8 server and one of my major concerns for a 24/7 box is my power usage. I did quite some tuning to go to around 30 watts in idle mode by enabling the C2 state in FreeNAS and letting the hard disks spin down (I got 2 WD RED 3TB, 1 WD RE 500GB and one 40GB SSD).

Actually for achieving an even lower power usage I want to enable C3-states as well but unfortunately FreeNAS doesn't seem to recognize anything lower than C2 for my CPU: Intel Xeon E3-1220V2. In the BIOS everything including C6 CPU and package state has been enabled but unfortunately FreeNAS doesn't seem to recognize it and I can't find any documentation on internet either on what might be the cause.

FreeNAS says this for all 4 cores:
dev.cpu.0.cx_supported: C1/1/1 C2/2/96

What could be the problem and how can I fix it? :)

Thanks in advance!

 

[cyberjock]

I don't have a solid answer for why its not working. But FreeBSD seems to run better on whitebox hardware, which yours isn't. My friend who has a whitebox system(but is Haswell.. so /shrug) only lists C1 and C2 also. My box is Ivy Bridge, but I can't actually run that command since I virtualize.

Edit: To be honest, if you read up on C-states, 70%(or 90%.. I forget which) of all of the potential power savings you can get are made just by going to C2. So I wouldn't fret it. On my test system when I went to C3 I couldn't even observe a difference on my wattmeter. Presumably because wattage got so low that while your CPU was using less power the inefficiency of a PSU at low wattages probably made up for the savings. :(

 

[Michael Wulff Nielsen]

I don't think there is much you can do, I played around with this and couldn't get it to work either.

You can (in theory) turn on c2 state with:


sysctl hw.acpi.cpu.cx_lowest="C2"

This should allow FreeNAS to drop into an even better power state. But frankly power management on FreeBSD (hence FreeNAS) is horrible. It was designed as an always on server operating system, never with power management in mind.

 

[Pavel+]

off-topic a bit, but I'm glad to see that you have FreeNAS Installed on the proliant. I have the same machine and so far have not been able to boot FreeNas on it and was about to give up and use something else - so finding this post is timely for me. :)

 

[ser_rhaegar]

off-topic a bit, but I'm glad to see that you have FreeNAS Installed on the proliant. I have the same machine and so far have not been able to boot FreeNas on it and was about to give up and use something else - so finding this post is timely for me. :)

Make sure the host controller is set to AHCI mode and not auto or any other setting in the BIOS. If it is not AHCI, FreeNAS won't boot. Also make sure to use a USB thumb drive and not the internal microSD slot.

 

[DrKK]

I don't think there is much you can do, I played around with this and couldn't get it to work either.

You can (in theory) turn on c2 state with:


sysctl hw.acpi.cpu.cx_lowest="C2"

This should allow FreeNAS to drop into an even better power state. But frankly power management on FreeBSD (hence FreeNAS) is horrible. It was designed as an always on server operating system, never with power management in mind.

Michael:

Back when we were talking about this before, I saved at least 5-10% in power by activating the C2 state on my FreeNAS. It was a notable amount. With powerd and the C2 state enabled, those things dropped my average power pull from 40W all told to about 30W all told...and probably half of the remaining 30W is the drives, so as a percentage of motherboard stuff/CPU power saved, it was considerable. For me.

 

[Lumpy Cheetosenburg]

off-topic a bit, but I'm glad to see that you have FreeNAS Installed on the proliant. I have the same machine and so far have not been able to boot FreeNas on it and was about to give up and use something else - so finding this post is timely for me. :)

Hi Pavel. I have a HP ProLiant Gen8 G2020T, and I haven't figured out how to configure it with RAID disabled so that FreeNAS sees Just a Bunch Of Disks. Did you figure out how to do that? If so, I'd sure like to know more.

Thanks,

-Lumpy