2020-06 Let’s get Virtual with each other

Due to the Corona virus a whole bunch of us IT folk have been getting a lot of “virtual” recently! We are viewed as being “system relevant” and some of us *must* work from home to keep the systems rolling. This month I thought I would walk down the road we at Software Engineering and SEGUS have all about virtual, and simulated, Db2.

Virtual, really?

The first thing is to think what do we mean by “virtual”, when I hold a live webinar I am talking live and you are listening live, there is nothing really virtual about it is there? The same is true about Db2 sub-systems. If you wish to test a major upgrade of your software (or even just a FL switch) you really should get it all tested in a virtual world before letting it loose in the real world!

How to get there?

You need a complete copy of your Db2 Catalog and Directory. That is enough – User data is not required and actually could be classified as dangerous from the Audit point of view! How you get this done is your business but I use ICE our InstantCloning Expert to get the job done really really fast!


Nope, once you have got this data copied across you need to “virtualize” the ZPARMS, bufferpools and even the hardware you currently have in production. IBM came up with an interesting way of doing this with hideously complicated HEX updates of EXPLAIN columns but I use VOX our VirtualOptimizer Expert to do all this for me!

Done yet?

Of course not! What is the good of having a virtual production system when you have no SQL to actually run on it? Just doing an EXPLAIN is ok of course – see later – but actually running the SQL that runs on the productive system should be your goal. For this I use the WLX (SQL WorkLoadExpert) tool to collect as much SQL as I like on production and then use this “workload” on my virtual production to actually check what happens when software is running.


Still not yet! The next part of the puzzle is to also EXPLAIN all of the dynamic and static SQL both before and after the “change” whatever that change may be! You then compare the outputs of about 120,000 explains to see where anything diverges in its access plan. I use our BIX BindImpact Expert to do all this automatically for dynamic and static SQL.

You must be done by now!

Never! The final piece of the virtual puzzle is now to switch on the IFCID 376 while running the SQL workloads to give you a heads up if any application changes are rolling down the road towards you. We are all aware that application changes take a while to get approved and done and the further out you can see the obstacle the easier it is to plan and avoid the crash!

It’s all too much!

Well, you can even do a “cheaper” variant – Instead of cloning the whole Db2 subsystem just copy the DDL, using DEFINE NO of course, and the production Statistics using our ProductionSimulator tool to a sand-box style Db2 subsystem. You can also rename the objects on the fly and this all enables EXPLAIN processing to be done without a real workload. This will only show you changing access plans for your static and dynamic SQL but is clearly much better than nothing!

Sounds Cool!

It is! You have a nearly 100% automated method to completely check any Db2 subsystem for any changes and using our advanced checking algorithms we can weed out all the background noise to let you see just “the facts ma’am”

But Virtual with each other?

As you are probably aware the IDUG NA 2020 has gone Virtual on us all and so it has a bunch of live sessions and a whole raft of pre-recorded sessions. Happily they also Include mine – released on the 3rd August – ”A DBA’s Got to Know Their Limitations!” I am also holding a VSP about Zowe (The zGUI r(evolution) – What is ZOWE going to do for me?) on Monday 10th August at 4pm EDT (22:00 Berlin) with live Q&A.

Please visit our virtual Booth at


Click on the SEGUS booth, middle row right hand side,  then scroll down to register and get the chance to win an iPad!!! A real one as well…


As always, any questions or comments would be most welcome and I would love to “virtually” meet you all soon!


Roy Boxwell