I have a Pi3 and a Pi2 running OH, together with many ESP8266 devices that control a lot of things, and I’m concerned I may be getting close to the practical limits of this setup, I’ve also worn out one SD Card despite running a read only file system with logging moved to RAM. Response time once the system is up and stable is good although I’ve noticed occasional sluggishness with rules triggering, and reloading a rules file can take several minutes. Restarting a Pi usually takes 10 minutes or more. I have 567 Items and 235Kb of Rules Files, memory usage on the Pi2 is 26.9% and on the Pi3 is 32.7%. The Pi2 also hosts EMONCMS for energy monitoring, albeit with the remote nodes changed from Radio to MQTT.
I’m considering moving to a Fanless NUC with a low power Quad Core CPU and an SSD.
Has anyone switched to a NUC from a Pi3? I’ll stick with Linux.
Is this a worthy upgrade path - I don’t want to increase power consumption more than necessary.
Is there anything to catch the NUC newbie?
Any other recommendations? The Pi’s never use more than 2 CPU cores which seems wasteful given that they have 4
Hi Kevin,
I’ve changed from a Pi to a NUC6CAYH some time ago.
It is equipped with a Celeron J3455 Quadcore and costs around 125.- EUR here as barebone (without memory and SSD)
It is not completely fanless, but the fan can be configured in the Bios to not run at low to medium load.
I dropped in 4 GB mem and an old Intel SSD, afterwards I’ve installed Ubuntu 16.04 Server.
Its running cool and quiet without issues
A nice thing is that you can set up and maintain openhab with the great openhabian script in no time.
I’ve measured power consumption, but I can’t recall it exactly, think it was 5 or 6 Watts.
My main reason to change from a Pi to a NUC was more main memory and a direct accessible SSD.
I’m fully satisfied with this setup and can recommend it.
Hi Peter,
thanks for the reply. That does sound like an interesting option. I especially like the largely fanless operation and low power use.
How many items do you have, and how large in KB are your rules files?
Is there any formula between recommended memory size and number of Items / Rules?
@Kevin I have close to 300 items I defined, not including runtime things/items. Im running ser2sock, openhab, nodeJS, another python websocket server, MySQL, and use SSD for rootfs. I only use the sdcard for booting. I also have a security camera system in place (total 20+ HD cameras) but I love BlueIRIS so my camera server is on a windows server but every motion/alert/event in BlueIRIS is also pushed to openHab. Never had an issue. I have close to 75+ sensors at home, all managed by OpenHab.
:/etc/openhab2/items$ wc -l *.items | tail -n 1
274 total
/etc/openhab2/items$ uptime
22:14:12 up 7 days, 26 min, 1 user, load average: 0.17, 0.29, 0.27
/etc/openhab2/rules$ free | grep Mem | awk '{print $3/$2 * 100.0}'
43.043
You see, for me, mem usage is 43%. You want this number high. Remember, unused memory is useless memory. Your stats seem fine to me. An intel NUC based system can easily quadruple the power consumption of a Pi. I only used a Pi instead of running openHAB in my BlueIris server because I wanted redundancy. My BlueIris runs an i7-2600 but I can maximize CPU to close to 100% during peak since some of my HD camera feeds need reencoding. What types of rules do you have. You might want to start optimization there. Let me know what you end up with…
I’m running an even slightly larger setup on a Pi3. You shouldn’t be needing more than that amount of CPU and memory.
You can move the OS to a SSD if you feel more comfortable with that, but if your SD card is still wearing out there’s something to remain that’s writing too much, or it’s just bad luck (just like any SSD or HDD will crash at some point in time). Check your swap setup and the other recommendations in this post. Let alone that you should be having a backup solution in place and operation (look at Amanda in openHABian if you have not yet done so).
Now don’t get me wrong, yes I also know reloading rules is lame and there’s memory leaks sometimes.
(oh, and there’s a bug to lock the UI while processing rules which results in perceived ‘sluggishness’, too).
But you will also see that on more powerful HW (albeit maybe a little less often visible due to more reserves).
It’s a matter of software, to be resolved in software, and it won’t go away by changing boxes.
+1
…on a side note, I prefer git-based backup instead of Amanda. Bitbucket and even microsoft offers free private git repos. That’s where I backup all my settings. Easily scriptable to commit/push, and revert back to a commit hash.
i have about 600 items, but only 65 kb of rules. Still working well on an RPI3
I have had my share of cardproblems but now everything seems well.
Nevertheless, I am keeping my eyes open for an alternative
I did a lot of research on alternatives yesterday, and reckon the Intel NUC option in post 2 is my favourite so far. It has a few issues that are being worked on by Intel, one is the USB 3 ports behaving as USB 2 ports, and the other seems to be the display going blank briefly when connected to VGA. Both of these won’t affect moving from a Pi which is usually headless and has shared bandwidth USB 2. The TDP of the 4 core celeron chip is 10 Watts which compares favourably with 2 Pi’s. I also have a bunch of salvaged 18650 Cells so maybe I’ll make my own UPS and run it from surplus solar power.
I’ve discounted the many AliExpress options as they aren’t that much cheaper once the lack of ongoing support is taken into account.
Under Linux I will be able to monitor the E9 smart attribute which is the life left in an SSD. Currently on my desktops this is between 93% and 96%, with my newest drive being 2 years old.
I could of course stay on the 2 Pi’s which is what I’ll do in the short term, and even add 2 SSD’s, but moving to a full SSD based system with added wear out prediction together with faster reloading of items and rules files is a very attractive way forward. Especially as it’s not that expensive once my time spent awaiting reloads is taken into account, together with the cost of 2 housings plus USB to SATA adapters is added.
Thanks everyone for your help
I’ve also discovered that a new NUC is due in Jan 2018, NUC7PJYH, code named June Canyon, which will have a slightly faster Pentium Silver Quad Core Chip - Pentium J5005 / Gemini Lake - with a suggested speed increase of around 15%, and a CPU TDP of 10Watts which is the same TDP as the NUC6CAYH.
As I need to deploy another ESP8266 with ESPEasy to handle the GPIO currently taken care of by my Pi3, and now everything is working reliably again after a lot of tweaks I’ll see what is available once my Pi’s have nothing other than USB devices attached.
I brought a cheap home server with exsi vmware, with openhab on a virtual machine on it. I definitely noticed improvements in performance but being on a virtual machine has made it difficult to add items such as bluetooth, etc. I would probably go for a dedicated machine next time.
I switched from Raspberry Pi2 to the Intel NUC7i3BNH. I could not get the Pi to work stable: good SD´s, bad SD´s, export to USB - whatever i tried, it crashed regularly and i was tired of this.
The NUC with 8GB RAM and 120GB M.2 SSD this is not cheap but it´s perfect for what i had in mind:
I know there will be something else to run on the NUC and therefore i use Proxmox as Hypervisor and run openhab2 and MariaDB (persistence) in separate LXC Containers.
Because i have a KNX-Installation i have also running a Windows XP with ETS4 in a KVM (virtual Machine). I can passthrough the USB-Ports to the VM so the KNX-interfaces (i need one for TP and one for Powernet) work as on a dedicated machine.
Proxmox works like a charm for free and i am happy that i found this austrian! software (used VMware ESXi before). Snapshots, Backups… most things work smooth over the web-gui.
Regards
Tom
P.S. This is my first post: hello everybody!
Thanks for the information Tom, and welcome!
On first look an i3 seems like overkill, but when has anyone wished their computer was slower 
Do you know how much power this uses when it is sitting idle? How often can you hear the fan? Does the machine feel hot when you touch the case? The i3 has a TDP of 15W which is more than the Atom based Celerons, and certainly more than my 2 Pi’s added together. I wonder how much more it uses most of the time.
My Pi’s are totally stable right now, and I have moved persistence as well as logging to RAM, so I have time to explore options before their SD Cards wear out again. I was originally thinking of 4 Core as I run a lot of things on my Pi’s, but maybe a 2 core i3 works out better than a 4 core Atom
There are a lot of i3-7100U based fanless mini PC’s on AliExpress so maybe it doesn’t use much power most of the time
Of course this is another dimension when it comes to power usage. But this was of course something i did consider in my search to an alternative to the Pi. After all, that’s why I spent a bit more on the latest generation of the NUC.
NUC7i3 running Proxmox, openhab2, MariaDB: 8W
additionally running Windows XP KVM: 8.7W
I didn´t hear the fan at all until now. But there was no load so far 
That’s why the case feels only slightly warm.
Fantastic information, thanks very much!
I’ve just bought a fanless barebones i3-7100U based Mini PC from AliExpress which I will slowly migrate to. https://www.aliexpress.com/item/Windows-Mini-PC-Nettop-HYSTOU-Core-i3-7100U-Core-i5-7200U-16GB-RAM-256GB-SSD-Alloy/32805166611.html?spm=a2g0s.9042311.0.0.y2Ifei I intend adding 2 x 4GB RAM sticks and an old Intel 80GB SSD with 95% life remaining. Its overkill for my needs which should ensure it spends most of its life at a similar power level to @webalizer system above.
I’ll update this thread so anyone following on knows how it goes.
The Pi’s are largely coping with the workload, although the odd MQTT message between them gets lost leading to random failures which is a pain. For now this is mainly about future proofing and increasing reliability by allowing me to keep a check on SSD life remaining. I intend taking regular system image backups and have a spare identical SSD that I can switch to if the original fails.
To maximise SSD life I’ll continue with my current logging and persistence in RAM setup together with file access times turned off.
To update this thread, the mini PC arrived and I added 8GB RAM and an old 80GB Intel SSD. Before loading 64Bit Debian, Zulu, OpenHAB V2.2, NGINX, EMONCMS and all the many other things I had on my old systems. To preserve SSD Life I have redirected /var/log, /tmp, and OpenHAB persistence to RAM, but I haven’t gone with a read only file system as it proved problematic.
As expected performance is stellar compared to the Pi’s, and whereas rebooting one Pi after the other took around 17 minutes, it now takes around 2 minutes from BIOS to last rule loaded, and the UI continues to work whilst its loading the rules albeit sometimes it takes a few seconds to respond. Loading edited rules now takes seconds compared to several minutes, and editing Items is completed quickly.
The day to day performance is similar to the old setup simply because the Pi’s worked well when they were left alone.
Before the upgrade the Smart media wearout indicator on the SSD was sat at 95% life left, and now after everything is installed it is still at 95%. The machine is both fast and doesn’t even get warm so the decision to go with a fanless i3-7100U has worked out…
I’m very happy with the end result and thanks to everyone that answered my posts.
Congrats!
Good work!
At least check your fstab for mount options:
Add the “noatime” (or “relatime”) mount option in /etc/fstab, to disable (or significantly reduce) disk writes whenever a file is read.
Thanks Thomas, I did that at the beginning as well as configuring /etc/rc.local to recreate log directories and files in the ram drive /car/log on boot. I also went with the basic installer which allowed me to not install any GUI’s. I also run a script to move all the rules files away apart from one that checks for the persistence finishing before they are moved back again.
Thanks for the link, it’s more comprehensive than the one I found.
Hi all,
It’s almost a year since the last post in this thread. Is the NUC still the best option to replace a Rasp Pi 3?
The Rasp Pi 3 worked fine for me up until now; with the 2.4 release + additional rules & items, I am finding that the Pi is getting sluggish. Yesterday I also got an out of memory exception.
Thanks,