Back up and restore

By the end of this page you will know what to copy to keep a migration safe, and what a restore brings back.

What to back up

Everything mccb stores is under ./data (see Install mccb). Back up the whole directory, and in particular:

• app.db: servers, accounts, uploads, jobs and the state of every item (pending, inflight, ok, error, skipped), which is what makes a resume possible;
• secret.key, or your SECRET_KEY value if you set one: without it, stored mailbox passwords can no longer be decrypted and must be entered again.

app.db is SQLite in WAL mode, shared by web and worker. Stop the stack before copying the directory (docker compose stop) so that the copy is consistent. This is a precaution, not something the code enforces.

Restore

1. Stop the stack.
2. Put the saved data directory back, with the same secret.key or the same SECRET_KEY in .env.
3. Start it again: docker compose up -d.

Items already imported are recognised, so a job continues where it stopped (see Pause, resume and retry). If the PST files are restored too, nothing has to be uploaded again.

Warning. Keep UPLOAD_CHUNK_SIZE unchanged between backup and restore. A different value changes the fingerprint of the same PST file, which is then treated as a new one.