Older source-send user journal replication processes - assure_mimix - 10.0

Assure MIMIX Administrator Reference

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Assure MIMIX™ Software
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Assure MIMIX
Assure MIMIX Administrator Reference
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This topic describes the older, less used method of replicating from a user journal known as MIMIX source-send processing. In this method, data groups are configured to use MIMIX source-send processes.

Note: Data groups configured for source-send processing do not use remote journaling and cannot take advantage of capabilities that require remote journaling. Remote journaling is required for best practices, including multithreaded database apply processing, target constraint management, and MIMIX Dynamic Apply (default cooperative processing of files).

MIMIX uses journaling to identify changes to database files and other journaled objects to be replicated. As journal entries are added to the journal receiver, the database send process collects data from journal entries on the source system and compares them to the data group file entries defined for the data group.

Journal entries for which a match is found for the file and library are then transported to the target system for replication according to the DB journal entry processing parameter (DBJRNPRC) filtering specified in the data group definition. The Data group file entries (FEOPT) parameter, specified either at the data group level or on individual data group file entries, also indicates whether to send only the after-image of the change or both before-image and after-images.

Alternatively, if all journal entries are sent to the target system, the journal entries are filtered there by the apply process. The matching for the apply process is at the file, library, and member level.

Note: If an application program adds or removes members and all members within the file are to be processed by MIMIX, it is better to use *ALL as the member name in that data group file entry. If individual members are specified, only those members you identify are processed.

On the target system, the database receive process transfers the data received over the communications line from the source system into a log space on the target system.

The database apply process applies replicated database transactions from the log space to the appropriate database or replicated object on the target system. Transactions that are not part of a commit cycle are immediately applied to the target system. For transactions that are part of a commit cycle, processing varies depending on how the data group is configured. Shipped default values for new data groups allow MIMIX to immediately apply transactions that are part of a commit cycle. Data groups can be configured so that MIMIX processes transactions that are part of a commit cycle but does not apply those transactions until the open commit cycle completes.

Throughout this process, MIMIX manages the journal receiver unless you have specified otherwise. The journal definition default operation specifies that MIMIX automatically create the next journal receiver when the journal receiver reaches the threshold size you specified in the journal definition. After MIMIX finishes reading the entries from the current journal receiver, it deletes this receiver (if configured to do so) and begins reading entries from the next journal receiver. This eliminates excessive use of disk storage and allows valuable system resources to be available for other processing.

Besides indicating the mapping between source and target file names, data group file entries identify additional information used by database processes. The data group file entry can also specify a particular apply session to use for processing on the target system.

A status code in the data group file entry also stores the status of the file or member in the MIMIX process. If a replication problem is detected, MIMIX puts the member in hold error (*HLDERR) status so that no further transactions are applied. Files can also be put on hold (*HLD) manually.

Putting a file on hold causes MIMIX to retain all journal entries for the file in log spaces on the target system.

The file entry option Lock member during apply indicates whether or not to allow only restricted access (read-only) to the file on the backup system. This file entry option can be specified on the data group definition or on individual data group entries.