•Quality of the LANs and WANs connecting different buildings or remote sites and the amount of available bandwidth.

•The number and size of the entries stored in the directory.

A site that manages human resource databases or financial information is likely to put a heavier load on the directory than a site containing engineering staff that uses the directory for simple telephone book purposes.

7.2.2 Managing disk space for the changelog

As with multi-master replications, synchronization requires a changelog of to track directory edits and log entries for the state information for update entries, and tombstone entries for deleted entries. This information is required for synchronization. Because these log files can get very large, periodically cleaning up these files is necessary to keep from wasting disk space.

There are four attributes which can maintain the changelog. Two are under cn=changelog5 and relate directly to trimming the changelog:

•nsslapd-changelogmaxagesets the maximum age that the entries in the changelog can be; once an entry is older than that limit, it is deleted. This keeps the changelog from growing indefinitely.

•nsslapd-changelogmaxentriessets the maximum number of entries that are allowed in the changelog. Like nsslapd-changelogmaxage, this also trims the changelog, but be careful about the setting. This must be large enough to allow a complete set of directory information or synchronization may not function properly.

The other two attributes are under the synchronization agreement entry in cn=sync_agreement, cn=WindowsReplica, cn="suffixDN", cn=mapping tree, cn=config. These two attributes relate to maintenance information kept in the changelog, the tombstone and state information, rather than the directory edits information.

•nsDS5ReplicaPurgeDelay sets the maximum age that tombstone (deleted) entries and state information can be in the changelog. Once a tombstone or state information entry is older than that age, it is deleted. This differs from the nsslapd-changelogmaxageattribute in that the nsDS5ReplicaPurgeDelay value applies only to tombstone and state information entries; nsslapd-changelogmaxageapplies to every entry in the changelog, including directory modifications.

•nsDS5ReplicaTombstonePurgeInterval sets the frequency which the server runs a purge operation. At this interval, the Directory Server runs an internal operation to clean the tombstone and state entries out of the changelog. Make sure that the maximum age is longer than the longest replication update schedule or multi-master replication may not be able to update replicas properly.

The parameters for managing replication and the changelog are described in chapter 2, "Core Configuration Attributes," in the Configuration, Command, and File Reference.

7.2.3 Defining the connection type

Synchronization can occur using simple authentication over a standard port, using SSL/TLS, or using Start TLS (a secure connection over a standard port).

Although it is not required, it is strongly recommended that SSL or other secure connection be used for synchronization. If passwords are going to be synchronized from the Windows server, then SSL must be enabled on both servers so the synchronization proceeds over a secure port.

7.2.4 Considering a data master

The data master is the server that is the master source of data; this is the primary or authoritative source for data.

7.2 Planning windows synchronization 95