Journal entries
When you use journal management, the system keeps a record of changes that you make to objects that are journaled and of other events that occur on the system. These records are called journal entries. You can use journal entries to help recover objects or analyze changes that were made to the objects.
Every journal entry is stored internally in a compressed format. The operating system must convert journal entries to an external form before you can see them. You cannot change or access the journal entries directly. Not even the security officer can remove or change journal entries in a journal receiver. You can use these journal entries to help you recover your objects or analyze changes that were made to the objects.
Contents of a journal entry
Journal entries contain the following information:
- Information that identifies the type of change.
- Information that identifies the data that was changed.
- The after-image of the data.
- Optionally, the before-image of the data (this is a separate entry in the journal).
- Information that identifies the job, the user, and the time of change.
- The journal identifier of the object.
- Information that indicates if the entry-specific data is minimized.
The system also places entries in the journal that are not for a particular journaled object. These entries contain information about the operation of the system and the control of the journal receivers.
Journal identifier
When you start journaling an object, the system assigns a unique journal identifier (JID) to that object. The system uses the JID to associate the journal entry with the corresponding journaled object.
Journal entry numbering
Each journal entry is sequentially numbered without any missing numbers until you reset the sequence number with the Change Journal (CHGJRN) command or System i® Navigator. However, when you display journal entries, sequence numbers can be missing because the system uses some entries only internally. For audit purposes, you can display these internal entries with the INCHIDENT option on the Display Journal (DSPJRN) command.
When the system exceeds the largest sequence number, a message is sent to the system operator identifying the condition and requesting action. No other journal entries can be added to the journal until the journal receivers are changed and the sequence number is reset.
Fixed-length and variable-length portions
A journal entry that is converted for displaying or processing contains a fixed-length prefix portion that is followed by a variable-length portion. The variable-length portion contains entry-specific data and, in some cases, null-values indicator data. The format of the converted entry depends on the command that you use and the format that you specify. The entry-specific data varies by entry type. The Send Journal Entry (SNDJRNE) command or the QJOSJRNE API specifies the entry-specific data for user-created journal entries.