docs: backup and restore (#2326)

docs/docs/administration/backup-and-restore.md

@@ -0,0 +1,25 @@
+# Backup and Restore
+
+## Database
+
+:::info
+Refer to the official [postgres documentation](https://www.postgresql.org/docs/current/backup.html) for details about backing up and restoring a postgres database.
+:::
+
+The recommended way to backup and restore the Immich database is to use the `pg_dumpall` command.
+
+```bash title='Backup'
+docker exec -t immich_postgres pg_dumpall -c -U postgres | gzip > "/path/to/backup/dump.sql.gz"
+```
+
+```bash title='Restore'
+gunzip < /path/to/backup/dump.sql.gz | docker exec -i immich_postgres psql -U postgres -d immich
+```
+
+## Filesystem
+
+Immich stores two types of content in the filesystem: (1) original, unmodified content, and (2) generated content. Only the original content needs to be backed-up, which includes the following folders:
+
+1. `UPLOAD_LOCATION/library`
+1. `UPLOAD_LOCATION/upload`
+1. `UPLOAD_LOCATION/profile`