Not really sure where to put this. After reading concerns about wearing out the built in flash, I decided to add the Disks monitor to see how often mmcblk0p1 is written to. I set up the block_dump debugging outlined here and left it on for a little over 10 hours.
I found that a few processes write to the disk.
Kresd writes to it once every 1:20:21 (one hour, 20 minutes and 21 seconds)
btrfs-transaction writes to it much more often, every 30-45 seconds, 2-13 writes each time with 256 sectors
kworker/u4:4 writes to it randomly every 0-30-ish seconds with 8 sectors, 150-270 writes each time.
Does this seem like normal activity?
It does seem like a lot of writes, but I don’t really know. In my past experience with OpenWRT, this sort of thing was dealt with using overlay filesystems on USB drives. Otherwise, I don’t think the flash space was written much at all.