ADMINISTERING


Transaction logging
Domino® transaction logging captures changes made to a database and writes them to a transaction log. The logged transactions are then written to disk in a batch, either when resources are available or when scheduled.

A transaction is a related series of changes made to a database on a server. For example, opening a new document, adding text, and saving the document is one transaction. In this case, the transaction consists of three separate implicit API calls: NotesOpen, NoteUpdate, and NoteClose.

A transaction log is a record of changes made to Notes® databases. The transaction log consists of log extents and the log control file (NLOGCTRL.LFH). A log extent is one of the log files into which the transaction logs are written. It has the form Sxxxxxxx.TXN, where the xxxxxxx characters represents a seven-digit number that is unique to that server. Domino fills each extent sequentially before writing data to a new one. The records are secured using a proprietary byte-stream format. Each server has only one transaction log that captures all the changes to databases that are enabled for transaction logging.

Use transaction logging to:


To use all the features of transaction logging for backups and backup recovery, you need a third-party backup utility that uses the backup and recovery methods of the Domino C API Toolkit. For example, in the case of a media recovery, a database backup is taken with the third-party utility, while logging keeps track of updates to the database. When the database is then lost, the backup is brought up to current state by going through the transaction log and applying any updates which have happened to that databases since the database backup was taken.

Note that restart recovery does not require a third-party utility. In this case, logging goes on while updates are happening. When the server crashes then restarts, any updates which would have otherwise been lost are written to the database. This significantly reduces lost data and database corruption because of server crashes, and reduces overall restart time since the consistency check of databases is not required.

Note: Transaction logging is required, and must remain enabled if you intend to use the Domino Attachment and Object Service, available in Domino 8.5 and later, to consolidate file attachments in a server repository.

Understanding the database instance ID (DBIID)

When you enable transaction logging, Domino assigns a unique database instance ID (DBIID) to each Domino database. When Domino records a transaction in the log, it includes this DBIID. During recovery, Domino uses the DBIID to match transactions to databases.

Some database maintenance activities, such as using the Compact command with options, cause Domino to reconstruct the database in such a way that old transaction log records are no longer valid. When this happens, a new DBIID is assigned to the database. From that point on, all new transactions recorded in the log for that database use the new DBIID. After a database is assigned a new DBIID, take a new full backup of the database. The new full backup captures the database in its current state with the new DBIID. Then, if you have to restore the database, Domino needs only the new transactions that contain the new DBIID.

Domino assigns a new DBIID when:


Related concepts
View logging

Related tasks
Setting up a Domino server for transaction logging
Preparing for transaction logging
Disabling transaction logging for a specific database
Using transaction logging for recovery

Related reference
How transaction logging works