66 lines
5 KiB
Markdown
66 lines
5 KiB
Markdown
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---
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date: 2023-12-08
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title: Optimizing Power Consumption
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tags:
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- homelab
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- hardware
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- power efficiency
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---
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I mentioned in [an earlier post](https://blog.mcknight.tech/2023/11/29/Homelab-Upgrades/) that one of my concerns with my current setup is the
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power consumption of everything in my rack. After writing, I realized that I know what the load is on my UPS, but I don't know how each component
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draws on its own or what everything actually costs to run. I also haven't looked into tuning things for power consumption for some time, so lets see
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if there are any savings to be had there. I picked up a couple of inexpensive ZWave switches that have current monitoring and added them to HomeAssistant
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to monitor my Unraid server and pfSense router. I can approximate the network switches' power usage by subtracting those 2 measurements from the UPS'
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measured usage.
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## Baseline Idle Power Usage
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I connected my Unraid server to one of the monitoring outlets yesterday afternoon, so I have some data including minimal usage overnight. I see that
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150-170W was used while streaming some media via Plex and then at bed time usage dropped to 140W with overnight load staying between 130-160W. There was
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one peak at 165W, presumably when some scheduled tasks run at 4:30AM.
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Checking the UEFI, I saw the fans all set to "Full Speed". I updated all of them to "Balanced" profiles and that helped with noise in my office which is
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a huge plus, but power usage is mostly unchanged. This is by no means a scientific test but does indicate there is little power efficiency to be gained
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by messing with fan curves.
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For my pfSense router, things are more consistent with power draw right around 58W with a range of 57-60W. I went into the BIOS and disabled
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overclocking and turned fans to "Eco mode" but saw very little change.
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Doing the math, my UPS measures about 250W of usage with about 150W and 60W going to my Unraid server and pfSense router, respectively. This leaves 40W
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going to the 2 Ubiquiti switches in the rack.
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## Looking for Power Savings
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There are a couple places I think I can save energy, so what can I do to validate that before investing more time and money? For the router, I
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know there's not much room to optimize what I have, so I can compare my measured power draw against other hardware options. For the server, I think there
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is some more investigation to do:
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### Spinning Rust
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Looking at my Unraid array, I see that all 7 spinning disks are active. I am able to manually spin down 4 of them (one has activity which also
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keeps the 2 parity disks active). This takes power draw from 154W to 134W; that's a full 20W savings! Guessing that Frigate would be the only
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service that won't write to my cache pool, I spun that down and then manually spun down everything in the array again. I'm now down to 111W,
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until the disks spin back up.
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This gives me some ideas about planning my storage solution. First, I'll want to try and get all of the services with regular disk IO using SSD-based
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storage. Second, if I can keep file metadata in RAM or SSD storage, that will hopefully prevent the disk from needing to be spun up just to open a network
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directory with the added benefit of not having to wait for disks to spin up just to look at directory contents.
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### pfSense Router
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As mentioned [in my earlier post](https://blog.mcknight.tech/2023/11/29/Homelab-Upgrades/#pfSense-Router-Appliance), a more efficient router was part of
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my initial upgrade plan. Looking at some of the [official Netgate options](https://www.pfsense.org/products/), I should be able to get the job done with
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20W for a savings of 40W.
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## Conclusion
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Adding up my potential savings, I optimistically have about 80W I can save at idle which comes to somewhere around 60kWh/month; that costs me a whole
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$6.50/month. That's not even a trip to Starbucks in terms of energy costs. This doesn't match my expectations from reading forum threads about optimizing
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every watt for cost savings, but according to [this random study](https://www.statista.com/statistics/263492/electricity-prices-in-selected-countries/),
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this may be because energy costs in much of Europe are much higher (I would be looking at up to $32.80/month savings in Italy according to this study).
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This changes my perspective about where to spend time and effort in my upgrades; yes I can get a more efficient router, but I'm only going to save about
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$3/month so that's not a good enough reason for me to spend $200. A new router could get me another 1U of available rack space, but I don't think I
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will need that either in the immediate future. For the hard drives, I do still want to keep those spun down as much as possible just for longevity; also,
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the issue of waiting for drives to spin up just to load network shares is a pretty common annoyance for me.
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This was a worthwhile investment of $50 and some time to actually do the math on what I stand to save with more efficient hardware. Another of many lessons
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that you shouldn't believe everything you read on the internet and spending the time to at least sanity check your assumptions with concrete data is always
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worth it.
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