Wednesday, July 21, 2010

Why a Directory Consumer is not read-only?

This is an interesting question.

In my customer's environment, he has a pair of Sun Directory Servers acting as Masters. The data in the pair is kept in-sync via Multi-Master Replication (MMR).

There are 4 Sun Directory Servers acting as consumers. The data are replicated from the 2 Masters.

Recently, he found out that when he modifies entries on any of the Consumers, the modified entries are updated to the Masters!

This violates the concept of a Consumer, according to what he understands of the term.

Well, let's take a close look at the following diagram:

The diagram illustrates a Master-Consumer deployment architecture. 

Did you notice there is a dotted arrow pointing from the Consumer back to the Master? This is the Referral that is causing the "side-effect". 

Ok, it's not "side-effect". It's a product feature of Sun Directory Server. 

Whenever there is a modification request on the Consumer, the Referral will redirect the request back to the Master. The Master will be the one that actually updates the entries. The Consumer can never process a modification request, it can only perform a search request


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