Are there advantages/disadvantages of running the emon OS from a USB stick rather than an SD card?
This requires a simple change to the cmdline.txt file.
My CrystalDiskMark tests using a USB 2.0 port (as RPi has) comparing the supplied Kingston 8 GB Class 4 SD card with the Integral Fusion 16 GB USB 3.0 are … USB reads twice as fast and writes are 10+ times faster. The Integral Fusion 16 GB costs approx GBP 8.
It maybe that read/write speeds are not an issue for emon…
But is USB better than SD regarding wear/longevity?
Is the larger capacity (16 GB rather than 8 GB) advantageous?
I don’t think there are any huge gains to be made running on a USB stick, the reads and writes have been minimised in the emonSD image to protect the card from failure, (which would also protect a usb stick or a ssd too).
There are many advantages to be gained by using a spinning disk type usb hdd though, size, speed, no read/write restrictions or optimizations required, etc.
If you do decide to go the “USB OS” route of any type, you should be aware that only editing the cmdline.txt file is not a recommended route, it is reliant on the USB storage being used to host the OS, to be the only attached USB storage at boot or that the right USB device is selected first by chance at boot.
For example if you plugged in another USB stick to transfer some files or do a back up and the Pi was rebooted, perhaps you left the 2nd stick connected and there was a power outage or rebooted remotely etc etc, either usb device has a chance of being recognized as /dev/sda and the other as /dev/sdb, so there would be a 50/50 chance the OS is found on /dev/sda. You should use UUID’s in both the cmdline.txt and the fstab to guarantee it will find the OS.