HP-UX Directory Server Administrator Guide HP-UX Directory Server Version 8.1 (5900-3098, May 2013)

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.
8.5.4 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, 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 but has more pending
changes to send, it will immediately attempt to reacquire the consumer and will most likely succeed,
because 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.
These two attributes may be present in the nsds5ReplicationAgreement object class, which
is used to describe replication agreements. Set the attributes at any time by using
changetype:modify with the replace operation. The change takes effect for the next update
session if one is already in progress.
NOTE:
If either attribute is set to a negative value, Directory Server sends the client a message and an
LDAP_UNWILLING_TO_PERFORM error code.
The two attributes are designed so that the nsds5ReplicaSessionPauseTime interval will
always be at least one second longer than the interval specified for
8.5 Configuring multi-master replication 347