Red Hat Directory Server 8.0 Administrator's Guide

NOTE
At the end of this procedure, all supplier servers will have mutual replication
agreements, which means that they can accept updates from each other.
NOTE
After creating a replication agreement, the connection type (SSL or non-SSL)
cannot be changed because LDAP and LDAPS connections use different ports.
To change the connection type, re-create the replication agreement.
5.4. Preventing Monopolization of the Consumer in Multi-Master
Replication
One of the features of multi-master replication is that a supplier acquires exclusive access to the
consumer for the replicated area. During this time, other suppliers are locked out of direct
contact with the consumer. If a supplier attempts to acquire access while locked out, the
consumer sends back a busy response, and the supplier sleeps for several seconds before
making another attempt. Normally, this is all right; the supplier simply sends its update to
another consumer while the first consumer is locked and then send updates when the first
consumer is free again.
A problem can arise if the locking supplier is under a heavy update load or has a lot of pending
updates in the changelog. If the locking supplier finishes sending updates and then has more
pending changes to send, it will immediately attempt to reacquire the consumer and will most
likely succeed, since the other suppliers usually will be sleeping. This can cause a single
supplier to monopolize a consumer for several hours or longer.
Two attributes address this issue, nsds5ReplicaBusyWaitTime and
nsds5ReplicaSessionPauseTime.
• nsds5ReplicaBusyWaitTime. The nsds5ReplicaBusyWaitTime attribute sets the amount of
time in seconds a supplier should wait after a consumer sends back a busy response before
making another attempt to acquire access. The default is 3 seconds.
•
nsds5ReplicaSessionPauseTime. The nsds5ReplicaSessionPauseTime attribute sets the
amount of time in seconds a supplier should wait between update sessions. Set this interval
so that it is at least one second longer than the interval specified for
nsds5ReplicaBusyWaitTime. Increase the interval as needed until there is an acceptable
distribution of consumer access among the suppliers. The default is 0.
Preventing Monopolization of the Consumer
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