As many are facing issues with sd card limitation on read/write cycles it would be nice to have it running on external ssd drive.
First I do not know what are the limitations using this approach (e.g. speed …).
I would immagine an image to put on the sd card in order to make it booting from the external drive, where we would place the hassio stuff…
What do you think ?
I think it’s needed.
The whole OS doesn’t have to move to a USB SSD, just the database that gets the majority of disk write activity.
The USB ports and Ethernet port share the same controller, so speed is never going to be as good as 480Mb/s (I’ve read 220Mb/s is about tops for USB and 90Mb/s for Ethernet) but this is about reliability not speed (which will still be better than microSD card read rates).
In the following article, scroll down to the “microSD” section:
https://www.jeffgeerling.com/blog/2018/raspberry-pi-3-b-review-and-performance-comparison
Even with a high-end micro SD card, don’t expect better that ~20 Mbps writes. Fortunately, for garden-variety home-automation purposes (intermittently writing logs), that’s adequate.
The principal advantage of using an SSD (as opposed to an SD or USB thumb-drive) is superior longevity. However, don’t expect them to be a miracle cure for all illnesses. If the RPi’s power supply is marginal or power is interrupted during disk-writes, the SSD won’t magically fix these errors.
Don’t bother buying a high-performance SSD for the RPi; you won’t experience the extra performance. A low-end SSD is capable of operating faster than what the shared USB 2.0 bus can sustain.
I have used USB flash drives and run a virtual HA from it, no SD card, on RPi3B+, from this it looks like ssd is possible as well: https://www.raspberrypi.org/forums/viewtopic.php?p=1385818
Have not tried this myself.
I am quite interested in this topic as well as I would like to have an RPI running in my parents’ house. As I am living about 2k km away it is not that easy to fix any SD card issue - especially not over the phone, etc 
I found this article but I am not really sure if it will help with hassio installs:
https://www.makeuseof.com/tag/connect-hdd-raspberry-pi/
Maybe someone of you is more into that topic and could tell us if that’s what we need 
Maybe it might also be better to get an RPI4 for that purpose?
Or better moving to a NUC to decrease probable headaches?
This can definitely be done:
As for this:
It depends. How big do you expect your HA system to grow?
For example, currently in the template editor this {{ states | count }} returns 1132 for my system. This did not run well on a raspi3B. However on an i7 4610Y mini pc it runs like this:
Can you afford the extra capital and ongoing costs of a mini PC?
NUCs are over priced, better value can be had: https://xcyminipc.aliexpress.com/store/817796 but you are still going to be spending more than if buying a pi. Also the pi uses less power so the ongoing electricity costs are lower (5W compared to 10 to 15W on 24/7).
Hi @tom_l!
Thanks for your info!
I would not mind spending that extra money for a “more stable” solution like an RPI with an external SSD or the XCY Mini PC you mentioned + the extra power costs if I could build a system that I can leave “alone” for 10 - 12 months …
My setup is an RPI3 with an SD card and I am happy with it so far. The load in my parents’ house would be quite nothing so from that point of view the RPI would be more than enough - but my issue is the SD card as I read so many posts where people talked about a corrupted SD card. Backups are fine - but if the person that has to deal with it has not any technical background (= my parents) the backup does not really help.
I will have a look at these XCY Mini PCs.
video about hassio
