Red Hat DIRECTORY SERVER 8.1 - DEPLOYMENT Deployment Manual

Also see for 8.1: Installation guide Release note Using instruction Reference Using instructions

Contents

Red Hat DIRECTORY SERVER 8.1 - DEPLOYMENT Deployment Manual Manual pdf 100 page image

Chapter 6. Designing the Replication Process90• When creating agreements for replication over a wide-area network, avoid constant synchronizationbetween the servers. Replication traffic could consume a large portion of the bandwidth and slowdown the overall network and Internet connections.• When initializing consumers, do not to initialize the consumer immediately; instead, utilize filesystem replica initialization, which is much faster than online initialization or initializing from file.Refer to the Red Hat Directory Server Administrator's Guide for information on using filesystemreplica initialization.6.3.6. Using Replication for High AvailabilityUse replication to prevent the loss of a single server from causing the directory service to becomeunavailable. At a minimum, replicate the local directory tree to at least one backup server.Some directory architects argue that information should be replicated three times per physicallocation for maximum data reliability. The extent to use replication for fault tolerance depends on theenvironment and personal preferences, but base this decision on the quality of the hardware andnetworks used by the directory service. Unreliable hardware requires more backup servers.NOTEDo not use replication as a replacement for a regular data backup policy. For informationon backing up the directory data, refer to the Red Hat Directory Server Administrator'sGuide.To guarantee write-failover for all directory clients, use a multi-master replication scenario. If read-failover is sufficient, use single-master replication.LDAP client applications can usually be configured to search only one LDAP server. Unless there isa custom client application to rotate through LDAP servers located at different DNS hostnames, theLDAP client applications can only be configured to look up a single DNS hostname for a DirectoryServer. Therefore, it is probably necessary to use either DNS round-robins or network sorts to providefailover to the backup Directory Servers. For information on setting up and using DNS round-robins ornetwork sorts, refer to the DNS documentation.6.3.7. Using Replication for Local AvailabilityThe necessity of replicating for local availability is determined by the quality of the network as well asthe activities of the site. In addition, carefully consider the nature of the data contained in the directoryservice and the consequences to the enterprise if that data were to become temporarily unavailable.The more mission-critical the data, the less tolerant the system is of outages caused by poor networkconnections.Use replication for local availability for the following reasons:• To keep a local master copy of the data.This is an important strategy for large, multinational enterprises that need to maintain directoryinformation of interest only to the employees in a specific country. Having a local master copy of thedata is also important to any enterprise where interoffice politics dictate that data be controlled at adivisional or organizational level.• To mitigate unreliable or intermittently available network connections.