As we further discuss backup strategies, please remember, that having a remote volume mounted as a primary or a secondary disk in your system means you have filesystem access to a distributed data store that you use by simply doing file operations (e.g. cat, tail, cp, touch, mkdir, etc.).

I would simply mention that features that exist in ZFS, Btrfs or XFS (not a CoW fs but has some CoW features). [...] both ZFS and Btrfs offer transparent filesystem compression, meaning even the stored, deduplicated pages can be further reduced in size.

"Thing" backup strategies:

• backup data pages in the file verbatim
• pack data pages as you copy them (byte by byte copy with database cleanup beforehand)
• dump the data as SQL commands

"How" backup strategies:

• litestream: copy the db changes depending on the WAL
• SQLite .backup command creates an exact page by page replica of the database file at the point of invoking the command.
• SQLite VACUUM INTO
• SQLite .dump
• good old cp with --reflink=always in a transaction