Confluence Docs 3.3 : Cluster safety mechanism
This page last changed on Jan 21, 2009 by ivan@atlassian.com.
IntroductionA mechanism was added in Confluence 2.3 and above to ensure database consistency when running multiple cluster nodes against the same database. This is called the cluster safety mechanism, and is designed to ensure that your wiki cannot become inconsistent because updates by one user are not visible to another. A failure of this mechanism is a fatal error in Confluence and is called cluster panic. Because the cluster safety mechanism helps prevents data inconsistency whenever any two copies of Confluence running against the same database, it is enabled in all instances of Confluence, not just clusters. How cluster safety worksA scheduled task, ClusterSafetyJob, runs every 30 seconds in Confluence. In a cluster, this job is run only on one of the nodes. The scheduled task operates on a safety number – a randomly generated number that is stored both in the database and in the distributed cache used across a cluster. It does the following:
How to fix itThis page has been migrated to Database is being updated by an instance which is not part of the current cluster. Technical detailsThe cluster safety number in the database is stored in the CLUSTERSAFETY table. This table has just one row: the current safety number. |
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Document generated by Confluence on Jul 09, 2010 01:08 |