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Comment: Published by Scroll Versions from space ML1 and version 9.0



MAX_FAILURES is The max_failures global determines the number of failures that can occur simultaneously while ensuring that no data is lost. By default, this is the number of node failures that can be tolerated.  If zones are in use, this is the number of node or zone failures tolerated. For example, if MAX_FAILURES = 1 (the default), the cluster can lose one node or one zone, regardless of how many the number of nodes are in the that zone. The value of MAXmax_FAILURESfailures is also used to determine the number of replicas created by default for a table or index.  For example, if MAX_FAILURES = 1, new database entities are created with REPLICAS = 2. See MAX_FAILURES for additional information. 

The value of MAX_FAILURES is displayed as max_failures is a read-only global variable :that can only be set using ALTER CLUSTER.


Default Value

max_failuresNumber of simultaneous failures that the cluster can withstand while maintaining transaction resolution and without suffering data loss. 1



Increasing the value for MAXmax_FAILURESfailures increases the number of replicas required, which can have a significant performance impact to writes and requires additional disk space. Due to the high performance overhead, Clustrix does not recommend exceeding MAX_FAILURES = 2

To change the value of MAXthe global max_FAILURESfailures, perform the steps outlined below. In this sample, the number of allowable failures is modified from the default of 1 to 2. This will cause all new tables and indexes to be created with REPLICAS = 3.


Tables created after the value for MAXmax_FAILURESfailures has been updated will automatically have sufficient replicas. However, tables created before MAXmax_FAILURESfailures was updated may not have sufficient replicas and need to be altered. This query generates ALTER statements for all representations that are under-protected. 


Log Messages

When the value for MAXmax_FAILURESfailures is modified, you will see an entry in clustrix.log that notes the number of failures that are configured: