On Apr 4, 2025, at 04:53, Ken N2VIP <ken@...> wrote:
It's an RPi 3B+ with half as much memory - it was selected for the purpose of RUNNING the radio, not building/compiling applications.
The 300 Meg swap is on the microSD card, not memory, not sure why you mentioned that…
Swapping to microSD seems like a bad idea (even though rpios does it by default): those can be both slow and unreliable, depending which one you buy. So now we know there are at least two reasons the zbitx might be doing significant writing when you pull the power plug: it could be swapping, or it could be writing FT8 decodes or your QSO log to sqlite. At least it’s not critical when writing swap is incomplete: unless you are using swap for hibernation (not something that most Linux users are doing), the contents don’t matter the next time you boot, they will be overwritten with whatever needs to be swapped out next time.
On ordinary computers, I try to have enough memory so that I don’t need swap at all, ever since I started using SSDs. It means that I sometimes get out-of-memory failures, if there just isn’t enough RAM to hold everything. Using swap could cause the SSD to wear out sooner. Yeah I know, most people don’t worry about it, and rpios has swap set up by default, like most distros do. Most people replace computers before the SSD wears out.
Pulling the power would be safer if it was running from RAM, and the root FS was mounted read-only. OpenWRT works this way, for example: your router needs to be reliable, and it’s quite normal to reboot it by pulling power rather than having to ssh to it and ask it to reboot. So it only reads files from flash, and does not write anything at all in everyday use. If you install extra packages, they get written to a separate overlay filesystem on the same flash, to avoid writing anything to the root FS. But working this way precludes writing periodic log files to the same storage! OpenWRT does not persist any logs, and does not need to. But usually there is a USB port, in case you want to add more storage and use that for something.
For sbitx/zbitx, one could at least use a separate partition for sqlite and other saved files: that would not reduce the wear on the SD card, but at least if it gets corrupted, the radio would still boot. Or, go further and use a separate drive for that (USB stick probably). Or, redesign the sbitx to use the CM4, and install at least 2 forms of storage: probably eMMC for the root FS and an SD card for auxiliary storage. But this would complicate the board design quite a bit, and add cost.
All the software that you want to run would have to be small enough to fit in RAM, if you want to avoid swapping. The sbitx process is pretty light, but unfortunately some of the other programs are more bloated.
Shirley Dulcey KE1L