H2 is a lightweight, in-memory database; it’s perfect for getting spun up quickly, but not so good for long-term usage. By default, Metabase uses H2 to store its internal data. The Sample Database included with Metabase is also an H2 database.
Avoid using H2 as your application database in production
If you want to run Metabase in production, we recommend that you migrate off H2.