If you take an advanced database like Oracle it's quite close to an operating system already and only really relies on the OS for boring stuff like boot-up, storing the db's code files etc:
- "Everything is a $FOO" philosophy, check. Where POSIX has files, RDBMS has tables.
- CLI/shell, check.
- Installable apps, check. (you can create stored procs by INSERTing java/javascript/etc into system tables).
Probably more parallels that don't occur right now. Lots of companies use the DB as their primary OS with the underlying kernel relegated to starting up the DB and configuring the hardware.
- Direct disk access bypassing kernel fs, check.
- POSIX-like API standard, check. (ANSI SQL)
- Structured data storage with ACLs, check.
- Volume management, clustering, replication, RAID. Check.
- "Everything is a $FOO" philosophy, check. Where POSIX has files, RDBMS has tables.
- CLI/shell, check.
- Installable apps, check. (you can create stored procs by INSERTing java/javascript/etc into system tables).
Probably more parallels that don't occur right now. Lots of companies use the DB as their primary OS with the underlying kernel relegated to starting up the DB and configuring the hardware.