Chapter 6. Configuring cascading replication using the command line

Procedure

1. Enable replication for the dc=example,dc=com suffix:

   # dsconf <supplier_instance_name> replication enable --suffix "dc=example,dc=com" --role "supplier" --replica-id 1

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   This command configures the supplier.example.com host as a supplier for the dc=example,dc=com suffix, and sets the replica ID of this entry to 1.

   Important

   The replica ID must be a unique integer between 1 and 65534 for a suffix across all suppliers in the topology.

2. Add the replication agreement and initialize the new server:

   # dsconf <supplier_instance_name> repl-agmt create --suffix "dc=example,dc=com" --host "hub.example.com" --port 389 --conn-protocol LDAP --bind-dn "cn=replication manager,cn=config" --bind-passwd "password" --bind-method SIMPLE --init example-agreement-supplier-to-hub

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   This command creates a replication agreement named example-agreement-supplier-to-hub. The replication agreement defines settings, such as the hub’s host name, protocol, and authentication information that the supplier uses when connecting and replicating data to the hub.

   After the agreement was created, Directory Server initializes hub.example.com. Depending on the amount of data to replicate, initialization can be time-consuming.

Verification

1. Display the replication configuration:

   # dsconf <supplier_instance_name> replication get --suffix "dc=example,dc=com"
   dn: cn=replica,cn=dc\3Dexample\2Cdc\3Dcom,cn=mapping tree,cn=config
   ...
   nsDS5ReplicaRoot: dc=example,dc=com
   nsDS5ReplicaType: 3
   ...

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   These parameters indicate:

   • nsDS5ReplicaRoot sets the suffix that is replicated.
   • nsDS5ReplicaType set to 3 defines that this host is a supplier.

2. Verify whether the initialization was successful:

   # dsconf <supplier_instance_name> repl-agmt init-status --suffix "dc=example,dc=com" example-agreement-supplier-to-hub
   Agreement successfully initialized.

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3. Display the replication status:

   # dsconf <supplier_instance_name> repl-agmt status --suffix "dc=example,dc=com" example-agreement-supplier-to-hub
   Status For Agreement: "example-agreement-supplier-to-hub" (hub.example.com:389)
   Replica Enabled: on
   Update In Progress: FALSE
   Last Update Start: 20210331105030Z
   Last Update End: 20210331105030Z
   Number Of Changes Sent: 0
   Number Of Changes Skipped: None
   Last Update Status: Error (0) Replica acquired successfully: Incremental update succeeded
   Last Init Start: 20210331105026Z
   Last Init End: 20210331105029Z
   Last Init Status: Error (0) Total update succeeded
   Reap Active: 0
   Replication Status: Not in Synchronization: supplier (Unknown) consumer (Unknown) State (green) Reason (error (0) replica acquired successfully: incremental update succeeded)
   Replication Lag Time: Unavailable

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   Verify the Replication Status and Last Update Status fields.

Troubleshooting

1. By default, the replication idle timeout for all agreements on a server is 1 hour. If the initialization of large databases fails due to timeouts, set the nsslapd-idletimeout parameter to a higher value. For example, to set the parameter to 7200 (2 hours), enter:

   # dsconf <supplier_instance_name> config replace nsslapd-idletimeout=7200

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   To set an unlimited period, set nsslapd-idletimeout to 0.

Verification

1. Verify whether the initialization was successful:

   # dsconf <hub_instance_name> repl-agmt init-status --suffix "dc=example,dc=com" example-agreement-hub-to-consumer
   Agreement successfully initialized.

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2. Display the replication status:

   # dsconf <hub_instance_name> repl-agmt status --suffix "dc=example,dc=com" example-agreement-hub-to-consumer
   Status For Agreement: "example-agreement-hub-to-consumer" (consumer.example.com:389)
   Replica Enabled: on
   Update In Progress: FALSE
   Last Update Start: 20210331131534Z
   Last Update End: 20210331131534Z
   Number Of Changes Sent: 0
   Number Of Changes Skipped: None
   Last Update Status: Error (0) Replica acquired successfully: Incremental update succeeded
   Last Init Start: 20210331131530Z
   Last Init End: 20210331131533Z
   Last Init Status: Error (0) Total update succeeded
   Reap Active: 0
   Replication Status: Not in Synchronization: supplier (Unknown) consumer (Unknown) State (green) Reason (error (0) replica acquired successfully: incremental update succeeded)
   Replication Lag Time: Unavailable

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   Verify the Replication Status and Last Update Status fields.

Troubleshooting

1. By default, the replication idle timeout for all agreements on a server is 1 hour. If the initialization of large databases fails due to timeouts, set the nsslapd-idletimeout parameter to a higher value. For example, to set the parameter to 7200 (2 hours), enter:

   # dsconf <hub_instance_name> config replace nsslapd-idletimeout=7200

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   To set an unlimited period, set nsslapd-idletimeout to 0.