I’m wondering what folks do to optimise the power efficiency of their Linux servers. I’ve never really got to the bottom of what is the best way to do this and with the current energy crisis its a pertinent topic.
I’m talking about home servers, so the availability requirements are not the same as in a corporate environment. There might be vast chunks of time during the day or night when they sit idle, and home users are more tolerant of a lag when accessing resources if it means lower energy bills.
Specifically I’ve been thinking about:
- allowing lower power states when idle
- spinning-down hdd’s when they’re not in use
- MAYBE letting machines sleep/hibernate
- setting schedules of times where you know demand will be low/zero and efficiency can be managed aggressively
- any other quick wins I’ve missed
It would be amazing if there was one tool or one guide that helps with all of that but thats never the case, is it 😅
Thoughts?
I split my loads (gigity) between the power hungry NAS and a passively cooled low power Proxmox host.
For me, most 24/7 activities are low CPU - like Home Assistant, so it needs to be there, but it doesn’t need to do anything.
Other VMs are ansible, uptime kuma, smokeping, etc… the most they use is RAM
Then the (relatively) more power hungry NAS powers up 3 times a day to syncthing everything, maybe upload a backup, and if no-one’s using Immich, etc. then it’ll power back off again.
The only other thing I have yet to downsize is my pfSense box (still a low powered device, but has fans…) and a Raspberry Pi I use for my Zigbee network.
I made a post about this a while back because I had some of the same concerns about power usage. (https://lemmy.world/post/41185625)
As most people are telling you, as they told me, ‘get better, more efficient equipment’, which is great advice if you are buying, but not so helpful if you’ve already bought. First thing I’d do is get a watt meter to get a baseline of what is being consumed. You can get watt meters from Amazon, or your preferred big box vendor, for cheap.
Once you have the baseline, then you can go about fiddling with Linux and your server, to find areas of excess power consumption. Please note tho, you’re not going to tame a $100 a month server down to $20. That’s just outside the realm of reality. However, every little bit helps. Go into your BIOS and check if there are power saving options there as well.
I know this will go against the grain, but I have a cron that powers off the server every evening before I retire. I am the only user of my services and I have no midnight, mass Linux ISO downloads going on, so I couldn’t justify having the server run for 10+ hours idle, consuming electricity. Electricity here is fairly cheap and I also have solar panels, but still, I think it’s worth the effort to be prudent with your resources.
In the end, the final tally was that I spend around $35 USD per month in electricity, which is far less than most people spend on a hobby.
spinning-down hdd’s when they’re not in use
I’ve just been through this recently. I decided to have my 2 backup HDDs spin down when not in use (99% of the time). I ran into an issue though where I needed them to wake up for SMART tests (which SMART didn’t trigger). Tried a few things that didn’t work so just set them to spin all the time. There’s about a 1-2w difference when they’re spinning all the time. So it’s just not something worth worrying about IMO (In the UK with high energy costs that comes out to 1.3 pence per day roughly).
There’s about a 1-2w difference
Yeah, you got to pick your battles.
I got a power-efficient mainboard and PSU. I think that’ll be the lion’s share. And I don’t have any unnecessary stuff like a GPU or extra stuff connected.
I ran
powertopand adopted the recommendations to set the various buses, peripherals and devices into powersave mode. That does a few Watts here and there. CPU of course is also allowed to save power when idle.And then I made the harddisks spin down after 40min of not being used. Or something like that. So they’ll automatically spin down at night and when I’m not using them. As spinning hdds consume quite a lot of power if you have multiple of them and compare it to the 15-20W or so the rest of the computer uses. The operating system is on a SSD.
Yes, ppl usually don’t really look at PSU efficiency curves.
Random example:
If you are gonna run on 20W most of the time you can calculate how much of a difference a certain PSU can make you (if you find a proper test that is).
That said, I do not recommend to use shitty PSUs, safety first, the components & layout need to be good (most of consumer PSUs are fairly garbage).
A bit like you wouldn’t use regular consumer HDDs.
(For most ez homelab cases every other component can be cheap consumer grade tho, exemptions ofc exist.)Yeah, I think the correct sticker on a PSU would be something like 80 Plus Ruby?! Everything else comes with 80+% efficiency at 20% rated load. Which is 200W for a 1000W PSU. And there’s no guarantee on what happens below that, so it might very well be utter garbage at a home server power draw of 20-30W.
You never know without looking up the datasheets. Though, back when I built my home server/NAS, I failed to find a good one. I got a PicoPSU and a 12V power brick instead. Not sure if that’s still a thing. But I remember it was a lot of work to find proper and efficient components. And it doesn’t make any sense to put in all the effort (and money) and then burn all the saved energy, and then some more, in an average PSU.
Some MiniPCs, NUCs and even computers also come with fairly efficient power supplies.
Do you have any idea what your hardware is actually pulling from the outlet? Maybe it’s not that bad after all?
Mine is pulling around 55W from the wall in its “normal” state. Meaning two 3.5" HDDs spun up, and a bunch of light services running. Which is squarely in “not great, not terrible” territory.
Apart from flipping the power saver switch on the mainboard I haven’t done anything to save power. I haven’t checked if that’s doing anything either. It’s a 3rd gen core i5 iirc, which isn’t great at idle power consumption, so maybe that switch is doing something…
I also haven’t had any luck with getting the drives to spin down reliably anyways, and afaik it’s better for them to just stay spinning so I haven’t bothered much to change that.
Just as a reference, my NUC with 40+ containers, runs at around 3-4 W, not counting the 2,5" 5400 rpm HDD attached.
Newer hardware that has lower idle consumption mostly. I’ve found there’s not much to do on a typical setup as far as software optimization, as most OS’s are already set up for pretty low power usage while idle.
HDD sleep can work if you don’t have anything accessing the drives, but with all the stuff running on my server there’s basically always some kind of activity going on so they never sleep. Less HDDs is the answer for me, I just have 2 large drives in a ZFS mirror.
My HP box with an i5-7500 idles around 15-20W which is decently low, but I also have 2 PCs with i3-7100u mobile chips that idle at 1-2W with 32GB of RAM and an NVMe SSD, which is wild.
Avoiding enterprise gear is key, it’s extremely power hungry.
Just yesterday I found this video talking about this very topic: https://www.youtube.com/watch?v=MucGkPUMjNo
I use powetop on laptops to recommend config optimizations, it could run on a server too.
hdparm can configure HDDs to powerdown, but I’ve never had any success using it on my router.
In theory I think You could use WoL and have your router wake a device before sending traffic but I haven’t seen any guides for doing this so maybe I’m missing something.
WoL works, but your server will take some time to come back online, but the router probably wont be able to buffer the traffic for that long, and a tcp connection would likely timeout before then anyway. You usually want to send the WoL magic packet, wait for the server to come back online, and only then start sending traffic.
What’s the timeout on a TCP connect?
Could you not wake from suspend in that window? Maybe even a full hibernate?
