• June 25, 2022

Each iCluster group should have its own default database journal

In the last Tech Tuesday post we discussed the question “How do I decide between more journals and fewer journals for my iCluster configuration?” Generally it is felt that KISS (Keep it Simple Stupid) is the overriding principle, i.e. the fewer the number of journals the simpler the configuration.

This led to a nice technical tip from one of our consultants. When configuring iCluster groups, try to ensure that each application group has its own default database journal. This keeps the monitor display nice and simple and helps in issues when a DMSETPOS has to be done by reducing confusion in your mind about where to restart replication when two different groups are using the same default journal, or if the journal receiver is gone for some reason, you are only impacting a single group!

It also is a performance/efficiency tuning issue.  If more than one group has the same default journal, both groups have to process (read) through all the entries.  If one of the groups happens to have a heavily active file journaled to the journal in common, then both groups must read through the high change rates, adding additional I/O processing that is redundant and less efficient use of resources.

Here is where the default database journal is defined for a replication group.

DMADDGRP Default Database Journal

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iCluster TechTuesday is a set of posts covering technical tips and techniques to help get the most out of your Rocket iCluster installation.


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