In April 2013, IBM announced Version 10.5 of DB2 for Linux, UNIX, and Windows. The same letter announced that DB2 AESE and DB2 AWSE would provide limited use of IBM InfoSphere Data Replication's (IIDR's) Change Data Capture (CDC) technology at no additional cost. However, the "limited use" statement sometimes leaves people with a question or two. The goal of this post is to answer those questions.
First, what CDC function are you entitled to use in the DB2 Advanced Editions? The license is the always final word, but, in simple terms, you can only use the bundled CDC to build disaster recovery solutions where a primary DB2 instance* has up-to-two backup instances. For example, the following replication topology is allowed by the DB2 Advanced Edition licenses:
Furthermore, the disaster recovery use case limits your entitled use of CDC function in the following ways:
- You can only use unidirectional (one-way) replication.
- You can set up replication from the primary DB2 to the backup(s) but you cannot set up replication from the backup(s) to the primary. This fits with the definition of a pure disaster recovery solution since it provides for fail-over but not switchback. If you need CDC for both fail-over and switchback, you need to license the full IIDR product.
- You cannot transform the data as it's replicated. Again, this fits with the definition of disaster recovery and you can license the full IIDR to be entitled to transformations as you replicate.
The question is - when do you need to buy CDC now? If you want to do anything more than what's described in this post, you'll need to buy IIDR for your DB2 Advanced Editions. The two most common replication configurations that require this are ones where you do either of the following:
- Replicate between DB2 LUW and either DB2 z/OS or Oracle.
- Set up an HA or Active-Active solution with IIDR's CDC technology.
If you need to understand more about these examples, we'll have pictures and add a few more examples in a future post that talks about when you need to buy CDC.
Of course, the last question is - can I still build DB2 DR, HA, and Active-Active solutions using the Q Replication built into the DB2 Advanced Editions? Yes, absolutely. The addition of CDC to DB2 does not change this.
* Multiple DB2 instances can be created from a single DB2 install. Each instance can use the bundled CDC to replicate up to the entitled number of backup instances.