The guardian database (ngwguard.db) serves as the master copy of the data dictionary information for the following subordinate databases in the post office:
User databases (userxxx.db)
Message databases (msgnnn.db)
Prime user databases (puxxxxx.db)
Library databases (dmsh.db and dmxxnn01-FF.db)
The guardian database is vital to GroupWise functioning. Therefore, the POA has an automated back-up and roll-forward process to protect it. The POA keeps a known good copy of the guardian database called ngwguard.fbk. Whenever it modifies the ngwguard.db file, the POA also records the transaction in the roll-forward transaction log called ngwguard.rfl. If the POA detects damage to the ngwguard.db file on startup or during a write transaction, it goes back to the ngwguard.fbk file (the “fall back” copy) and applies the transactions recorded in the ngwguard.rfl file to create a new, valid and up-to-date ngwguard.db.
In addition to the POA back-up and roll-forward process, you should still back up the ngwguard.db, ngwguard.fbk, and ngwguard.rfl files regularly to protect against media failure. Without a valid ngwguard.db file, you cannot access your e-mail. With current ngwguard.fbk and ngwguard.rfl files, a valid ngwguard.db file can be rebuilt should the need arise.
The ngwguard.dc file is the structural template for building the guardian database and its subordinate databases. Also called a dictionary file, the ngwguard.dc file contains schema information, such as data types and record indexes. If this dictionary file is missing, no additional databases can be created in the post office.