IBM WebSphere MQ v7.1 SMDS: What goes up will come down
Marcela Adan 100000THF9 firstname.lastname@example.org | | Tags:  shared smds z/os message websphere integration mq messaging middleware set data
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By Lyn Elkins
While working on the IBM WebSphere MQ V7.1 and V7.5 Features and Enhancements IBM Redbooks publication, I had that wonderful and rare opportunity to exercise the shared message data set (SMDS) capability more fully.
It also led to some really interesting observations. In the WMQ07 Wildfire workshop environment, where I normally work, we have limited coupling facility resources, and have to be cautious about making changes because the next workshop is generally only a week or two away. The folks at IBM Redbooks that provided the lab environment for the residency said that we could define several structures and alter them at will!!!! I could test different combinations without fear. It was wonderful.
It also led to some really interesting observations. Including what can happen during capacity tests, and ultimately in a production environment, when there are multiple demands on the system.
After some frantic investigation, the answer became obvious – another residency had started using some of the same resource pools. That team’s DB2 structures were also defined using ALLOWAUTOALT(YES). When they were testing they were grabbing MY storage, and when I was testing I was only using what was fair. Well that is my opinion...
We actually kept those results in the book IBM WebSphere MQ V7.1 and V7.5 Features and Enhancements. It adds to the complete picture of the interaction between subsystems and applications that can change expected (and tested!) behavior. Something else to keep in mind for production.
Other blog posts from the team:
How to write a WebSphere MQ book in 4 weeks (and survive to tell about it!) by Craig Both and Alex Ross
Improving z/OS WebSphere MQ availability: Structure failure or connectivity loss? by Barry Dearfield
Lowering administration cost wth Use Dead-Letter Queue (USEDLQ) channel attribute in WebSphere MQ V7.1 by Cezar Aranha
IBM WebSphere MQ Channel Access: Delete or Block? by Craig Both