IBM Data Replication's CDC News

Is CDC Free with DB2 LUW?

DavidT Tags: db2 cdc data_replication licensing ‎ 4,460 Views

This post is the answer to one of the FAQs found in Licensing Tips for IBM Data Replication.

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.

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* 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.

Modified on by DavidT

What Happened to InfoSphere CDC?

DavidT Tags: announcement data_replication cdc ‎ 8 Comments ‎ 7,392 Views

This post is the answer to one of the FAQs found in License Tips for IBM Data Replication.

You may have seen a recent announcement on ibm.com that says IBM would no longer be marketing it's older data replication products in 2013. That includes InfoSphere CDC. Why? And what happens to the CDC technology?

Over the years, IBM provided its data replication technologies through a lot of different products. For example, IBM used to offer two major data replication products at the same time - InfoSphere CDC and InfoSphere Replication Server. That was a little confusing, even to some IBM people. To simplify the situation, IBM consolidated all it's replication technologies into a single product called IBM InfoSphere Data Replication (IIDR). Once IIDR was available, the older products no longer needed to be sold to new customers. That's why the end of marketing was announced. However, the replication technologies - CDC, Q Replication, and SQL Replication - are still alive and well. You can continue to use them as you always have. Of course, you may have two related questions:

Are the older products still being supported?

Yes, as of the date of this post, they are. They are supported until IBM announces an end of service. If you ever have a question about whether an end of support has been announced, see the IBM Software Support Lifecycle pages on ibm.com.

How do you move from your old InfoSphere CDC product to IIDR?

If your InfoSphere CDC is on UNIX or Windows, you should see IIDR show up in your Passport Advantage account on March 12, 2013 if your shop is current on its InfoSphere CDC S&S (subscription and support).
If your InfoSphere CDC is on z/OS, then your IBM sales team will talk to you about a special bid as mentioned in the original IIDR announcement letter.

If you have any questions, feel free to post them in the comments section of this blog.

Data Replication's Enhanced Apply for Netezza

DavidT Tags: db2 data_replication netezza oracle infosphere ‎ 2 Comments ‎ 8,098 Views

If you're looking for an excellent way to replicate changed data from a wide range of databases into a Netezza appliance, you can do so through InfoSphere Data Replication. The latest release provides an Apply program that is both native to Netezza and optimized for Netezza targets. This Apply is built from Data Replication's CDC technology and is also compatible with the CDC technology found in InfoSphere Change Data Capture and InfoSphere Classic Change Data Capture for z/OS. This means you can replicate data to Netezza from source databases ranging from Oracle, DB2, and others on UNIX or Windows to DB2* and IMS on the mainframe. Ordering information can be found in the Data Replication announcement letter on ibm.com.

* Data Replication's CDC Apply program cannot be used to feed changed data to the IBM DB2 Analytics Accelerator (IDAA).

IBM's Table Compare Utility and CDC

DavidT Tags: db2 cdc data_replication ‎ 3,343 Views

Now that IBM has packaged its major data replication technologies into a single product, InfoSphere Data Replication, a lot of people are asking what they can take advantage of that they couldn't with the older products (InfoSphere CDC and InfoSphere Replication Server). Other than the obvious point of having access to multiple technologies, you can now use IBM's table compare utility, asntdiff, with CDC. asntdiff is a general-purpose utility that compares the data from two queries. IBM provides it through several product - Replication Server, the IBM Data Server Client, and all editions of DB2 and InfoSphere Warehouse.*

Long-time CDC users may ask what's happening to CDC's differential refresh and why they would want to use asntdiff instead of differential refresh. First understand that differential refresh is alive and well and it's not going anywhere :) asntdiff is just an option available to you.

To understand when you might want to use asntdiff, understand the basics of how it works.

asntdiff accepts two queries as input and compares the result sets.
You can use almost any query you can write against source and target tables.

So, the first reason to consider asntdiff is times when differential refresh's restrictions could be overcome by writing queries to get the result sets you need. For example, asntdiff may be an alternative if one of the following differential refresh restrictions applies to your replication configuration:

Differential refresh is only available for tables that use Standard replication.
Derived columns in the source table are not supported.
Target columns are ignored if they are mapped to derived expressions, constants, or journal control fields.
Key columns of the target table must be mapped directly to columns in the source table.

Next, asntdiff is independent of data replication and can be started from a command line. Among other things, this means:

It can made part of a z/OS batch job and scheduled.
It can be used while a CDC subscription is running

One major point to be aware of with asntdiff is how it works with heterogeneous data. For example, when you want to compare data being replicated from Oracle to DB2. asntdiff was originally written for DB2 databases. As a result, it requires IBM data federation technology to query databases such as Oracle. The good news is that InfoSphere Data Replication provides data federation for use with data replication configurations.

If you're not familiar with asntdiff and want to give it a try, see the ChannelDB2.com blog post titled Compare the Rows of Two Tables. If you have questions, feel free to post them in the CDC message board here on developerWorks.

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* Yes, technically, you could already use asntdiff with CDC on UNIX or Window since it comes in so many IBM products on UNIX and Windows. However, if you wanted to use it on z/OS, you could only get it through Replication Server. It's now in InfoSphere Data Replication as well.

CDC and IMS Replication Compatibility

DavidT Tags: compatibility ims replication cdc data_replication ‎ 1 Comment ‎ 5,516 Views

In 2011, IBM released three new data replication products:

One question that comes up is whether the two IMS replication products are compatible with either the new Data Replication product or the existing InfoSphere CDC products. The answer is yes - the IMS products are compatible with both new and existing products that contain the CDC technology. IMore specifically, they can provide IMS changed data to any data replication solution that you can build with IBM's CDC technology. For example, you can create unidirectional (one-way) subscriptions that feed IMS changed data to any database that can be targeted by CDC:

Two notes about this picture:

IBM recommends you use the CDC technology in IIDR if you do not own InfoSphere CDC.
The target DB2 can be DB2 for z/OS, DB2 LUW, or DB2 for System i.

You could also feed IMS changed data into other business software such as ETL, IBM's DataStage, and ESBs:

In other words, the new IMS data replication products extend the reach of IBM's CDC technology by adding IMS as a source for log-based capture of changed data. If you have technical questions, see the Classic CDC section of the Information Center.

A New IBM Redbook About CDC for DB2 z/OS

DavidT Tags: infosphere db2 zos cdc data_replication replication ‎ 5,268 Views

For those of you who don't subscribe to the IBM Redbook newsletter, you may have missed last week's announcement of a new Redbook titled Implementing IBM InfoSphere Change Data Capture for DB2 z/OS V6.5. It is a exellent extension of the brief CDC z/OS sections found in last year's Redbook titled Co-locating Transactional and Data Warehouse Workloads on System z. This new Redbook provides information about installing, configuring, running, and tuning CDC for DB2 z/OS. Read it if you need it and don't forget to rate it (no one will cry if you give it 5 stars :)

A New Look for the CDC Forum

DavidT Tags: cdc change_data_capture replication data_replication infosphere ‎ 2,662 Views

Hi, everyone,

Over the next month or so, we'll be updating the look of the CDC Forum and adding content. For example, you may have noticed we added a data replication icon and a wiki widget. More is in store. If you have requests, feel free to post a comment to this blog post. No guarantees, but we'll do what we can :)

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