Uh-oh. Spoke too soon. The Raspberry Pi just froze 8 hours after the backup has completed (with all services down). Poking around the logs, it seems something related to InfluxDB trying to compact old files, which overloads the CPU and saturates the I/O on the SD card (temp files?).
Suggestions? Should I upgrade to 1.11 or 2.7? Maybe convert everything to Victoria Metrics?
I would prefer to retain the data, if possible (historical knowledge).