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Sun OpenDS Standard Edition 2.0 Architectural Reference

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Document Information

The Directory Server Access Control Model

Understanding the Directory Server Schema

Index Databases

Understanding Directory Server Plug-Ins

Directory Server Replication

Overview of the Directory Server Replication Architecture

Basic Replication Architecture

Replication Servers

Replication Change Numbers

Replication Server State

Operation Dependencies

How Replication Works

Directory Server Change Processing

Change Replay

Auto Repair

Directory Server Crashes

Replication Server Crashes

Historical Information and Conflict Resolution

What is a Replication Conflict?

Resolving Modify Conflicts

Resolving Naming Conflicts

Purging Historical Information

Schema Replication

Schema Replication Architecture

Replication Status

Replication Status Definitions

Degraded Status

Full Update Status and Bad Generation ID Status

Replication Groups

Replication Server Selection

Replication Groups in a Multi-Data Center Deployment

Assured Replication

Assured Replication Modes

Safe Data Mode

Safe Read Mode

Safe Read Mode and Replication Groups

Assured Replication Connection Algorithm

Assured Replication and Replication Status

Assured Replication Monitoring

Root Users and the Privilege Subsystem

Supported Controls and Operations

Directory Server Crashes

When a directory server crashes, its connection to the replication server is lost. Recent changes that the directory server has processed and committed to its database might not yet have been transmitted to any replication server.

When a directory server restarts, therefore, it must compare its state with the server state of the replication servers to which the directory server connects. If the directory server detects that changes are missing and not yet sent to a replication server, the directory server constructs fake operations from historical information. The directory server sends these fake operations to its replication server.

Because teh local server state is not saved after each operation, the directory server cannot trust its saved server state after a crash. Instead, it recalculates its server update state, based on historical information.