Immich uses user/YYYY/MM folders on my setup, and I exclude any thumbnail directories from the backup too. So not many dirs/files to check for the backup software and it’s very quick.

That makes sense. I copy the whole set of data dirs so I can trivially start it after restore or start it elsewhere without extra steps. Also because this strategy works with all services so I don’t have to consider how to backup/restore each one. Makes adding new services less work.

pgdump with live file copy while the service is in active use can result in files the db doesn’t know about, or files it thinks are there that were actuall deleted. Probably can be fixed after the fact.

More generally, as a someone who’s done software for a very long time, I’ve learned that the further away I go from the happy path of a software program, the less tested it is, the more bugs there are and the poorer the edge case handling is. So for backups I lean on the process kill/recovery edge case that they all must handle. Snapshot + backup from that snapshot looks like a process death to the service upon restore.