Site Replication Service

As you learned earlier in the chapter, SRS is used to make Exchange Server 2003 servers appear as Exchange 5. x servers to other Exchange 5. x servers in a site. It is also used by ADC to synchronize configuration information. SRS is installed automatically when the first Exchange Server 2003 server is introduced to an Exchange 5. x site. When it is installed, a connection agreement is also created so that the ADC can manage the synchronization of configuration information.

There is really not much for you to manage about the SRS; Exchange Server 2003 handles the configuration and maintenance of SRS pretty much automatically. However, there are a few points about SRS of which you should be aware.

SRS and LDAP SRS runs the Lightweight Directory Access Protocol (LDAP) in order to communicate with Active Directory. Because Windows Server 2003 also uses LDAP and locks the well-known port 389 for its own use, SRS defaults to using port 379 for its LDAP communications. No special configuration is needed for SRS to communicate with Active Directory, but on occasion, you may need to configure special firewall access for the port. You can learn more about configuring ports for LDAP in Chapter 15, ‚“Securing and Troubleshooting Exchange Server 2003. ‚½

Site Consistency Checker The Site Consistency Checker (SCC) is an updated version of the Knowledge Consistency Checker from Exchange 5. x . The SCC ensures that knowledge consistency is maintained for sites and administrative groups when operating in mixed mode. It does this by dynamically configuring multiple connection agreements to establish the most efficient replication.

SRS database SRS uses the same ESE database technology that the Information Store uses and that the Exchange 5. x Directory Service uses. When SRS is installed, a set of databases and transactions logs much like those for a storage group is installed in the \Program Files\ Exchsrvr\srsdata folder. Unlike the stores in a storage group, the SRS database cannot be mounted or dismounted. However, you can stop and start SRS manually using the Services tool provided with Windows.

Creating an additional SRS for a site Only one instance of SRS can run on a single Exchange Server 2003 server, and normally only the first Exchange Server 2003 server installed into an Exchange 5. x site is configured with SRS. Additional Exchange Server 2003 servers installed into the site do not really need the service because they can simply rely on Active Directory for their directory information. However, it is sometimes useful to have another instance of SRS running in a site; for example, it may help to balance the replication load in a busy site. You can install an additional instance of the service in System Manager by expanding the Tools container, right-clicking the Site Replication Service object, and selecting the New Site Replication Service command from the shortcut menu. Each additional instance of SRS requires an additional Exchange Server 2003 server in the site.