Journaling Procedures › Using Read and Write Drivers › Journaling Under the Central Version

Journaling Under the Central Version

Update and Retrieval Transactions

Under the central version, several transactions can update the database concurrently. CA IDMS/DB writes information about all update transactions to the journal files. CA IDMS/DB also writes status information about retrieval-only transactions if JOURNAL RETRIEVAL is specified in the system generation SYSTEM statement.

Use Disk Journals Under the Central Version

You must use disk journals for automatic recovery under the central version. Automatic recovery occurs during warmstart, following the abnormal termination of a transaction, and following the execution of an SQL statement during which errors were encountered.

Note: For more information about automatic recovery, see 21.2, “Backup Procedures”.

Need at Least Two Disk Journals

Under central version, you need at least two disk journals. As one file becomes full, CA IDMS/DB automatically switches to an alternate file. While CA IDMS/DB writes to the alternate file, the full disk journal file must be offloaded using the ARCHIVE JOURNAL utility statement. This procedure is described in more detail later in this chapter.