Checking Data Between Failover Members
When checking between failover mirror members, the check is typically run with the backup failover member configured as the DataCheck destination for the following reasons:
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The DataCheck destination uses more resources than the source in order to maintain the results of the check and other state information (which is itself journaled).
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If the backup failover member is the DataCheck destination, the results are available for review on the backup if the primary failover member goes down.
Note:
In most configurations, it is assumed that the failover has already occurred and any review of the results probably happens after the failover decision point.
Whenever DataCheck loses its connection to the source, it retries the connection, waiting indefinitely for the source machine to become available again. If a mirror-based DataCheck is started on the destination when it was not the primary failover member, and that member becomes the primary, DataCheck stops rather than automatically try to reconnect. This prevents DataCheck from unintentionally running on the primary. For more information about reconnecting, see Starting/Stopping/Reconnecting DataCheck in this chapter.
