OUD - How to Initialize Replica(s) Using "dsreplication" or "import-ldif" Commands (Doc ID 2166392.1)

Note1: When initializing, keep in mind that encrypted attributes should be configured in the destination replica(s) prior to initialization, like in the source replica. When the attribute encryption configuration is the same in destination replica as the source replica, there is no need to decrypt the LDIF when exporting since the encryption keys are stored in cn=admin data.
Reference: Configuring Attribute Encryption in Replication Enabled Topology

Note2: To speed up import-ldif on Linux -
1) An offline import-ldif is faster than an online import-ldif or running 'dsreplication initialize'.
2) The offline or online import-ldif JVM parameters can be configured in OUD java.properties to improve initialization performance.
Reference: OUD11g - How to Shorten Import Time When Performing 'import-ldif' Command on Millions of Entries (Doc ID 2223626.1)

Note3: When using "import-ldif" the suffix or backend will be overwritten. If there is a need to just add information, use "-a" or "--append" to append the imported data to the data that already exists in the back end. Or use ldapmodify to add entries.   This is also explained lower in this document.
Reference:
Administering Oracle Unified Directory
A.1.3 Data Administration Commands
A.1.3.6 import-ldif

A.1.4 LDAP Client Commands
A.1.4.3 ldapmodify

Note4: If it's 11g-12c replication where "dsreplication status" may show "Not Connected", "Not Fully Connected" or "Unknown", take a look at the below KM:

OUD 11g/12c - Replication "I/O Error: Connection Reset By Peer" In Backend OUD Servers (Doc ID 2489379.1)