Sun Java System Directory Server Enterprise Edition 6.3 Deployment Planning Guide

Directory Server Replication

Directory Server lets you replicate directory data for availability and load balancing between the servers in your deployment. Directory Server allows you to have multiple read-write (master) replicas deployed together.

Internally, the server makes this possible by keeping track of changes to directory data. When the same data are modified on more than one read-write replica Directory Server can resolve the changes correctly on all replicas. The data to track these changes, must be retained until they are no longer needed for replication. Changes are retained for a period of time specified by the purge delay whose default value is seven days. If your directory data undergoes much modification, especially of large multi-valued attributes, this data can grow quite large.

Because the level of growth is dependent on several factors, there is no catch-all formula to calculate potential data growth. The best approach is to test typical modifications and measure the growth. The following factors have an effect on data growth as a result of entry modification:

Note that the replication meta-data remains in the entry until the purge delay has passed and the entry is modified again.

For a detailed discussion of Directory Server replication, read Chapter 4, Directory Server Replication, in Sun Java System Directory Server Enterprise Edition 6.3 Reference.