@bitpirate I run mas.to in an LXC virtual container for easy portability. It means I can do quick snapshot backups with ZFS, and can just lift and shift to another server if I need to. Running a single Postgres instance at the moment and I think that's the next thing I'll need to upgrade. We're running on a dedicated Intel i9-9900K machine with 128GB at the moment, but I have a 5950X ready as the next step up.
@trumpet take a look at patroni if you want to run a cluster. For backups i can recommend barman. ZFS snapshots work but might have a high recovery time:
https://www.postgresql.org/docs/current/backup-file.html
tl;dr run CHECKPOINT before creating a snapshot