Time to Download the Db2 13 for z/OS Manuals!

Yesterday I posted a brief piece about the new version of Db2 for z/OS that is now generally available: Db2 13 for z/OS is Here! It is always an exciting time when a new version of Db2 for z/OS is unleashed on the world and one of the first things I recommend is to start reading the manuals to see what all is there!

I like having the PDF versions of the manuals on my hard drive, so with each new version, I start by downloading them! With that in mind, here is the link to the IBM page that hosts the PDF manuals for Db2 13 for z/OS. 

Of course, over time, this documentation will be modified. Therefore, it is a good idea to be aware that subsequent modifications may render the versions on your hard drive inaccurate. You can always replace them periodically if you wish... perhaps when you adopt a new function level make plans to downloads the latest iterations of the manuals. 

There is also a great, new redbook on Db2 13 for z/OS that you should download and read. It is titled IBM Db2 13 for z/OS and More, and it, along with the What's New manual, can serve as a nice introduction to this new version.

A new manual that I need to mention is the SQL Data Insights Users Guide. If you read my earlier post (Db2 13 for z/OS is Here!) then you know that SQL Data Insights is a new Db2 13 capability that combines AI/deep learning with Db2 for z/OS and IBM Z technologies to deliver SQL-based semantic queries on tables and views. It is probably one of the most exciting new things in this new version...

So if you work with Db2 for z/OS don't delay... download those new manuals and start learning what new wonders Db2 13 will offer up!

Db2 13 for z/OS is Here!

Here we are, in June 2022, about 5 years or so since Db2 12 for z/OS was released. And lo' and behold, IBM has given us a new version of Db2 for z/OS to learn and adopt: Db2 13 for z/OS. 

The new version is generally available (as of May 31, 2022). If you were not paying close attention though, you may have missed it. Db2 13 was announced at the same time as the new mainframe (IBM z16), so it didn't get quite the same level of attention. But those of us who use Db2 for z/OS day in and day out will find a lot of great new stuff in this latest and greatest version of Db2.

I'm not going to go into great detail about the new features and functionality of Db2 13 for z/OS today, but I will offer a high-level overview. Look for future blog posts to dig into more of the nitty gritty tech details and capabilities.

The first thing to mention is that you will need to activate the last Db2 12 function level 510 (FL510) before you can migrate to Db2 13. As many organizations are lagging behind in terms of function level activation, it will be interesting to see how this requirement impacts migration to Db2 13.

AI

So what can users expect from this new version? Well, it seems that the most talked-about features are related to adopting AI. Functions that deliver AI capabilities into Db2 will make it easier for organizations on the AI journey to integrate Db2 into their processes.

Perhaps the most significant AI addition to Db2 13 is the SQL Data Insights feature. Provided as an extension to Db2, SQL Data Insights is delivered using built-in functions to deliver AI capabilities like uncovering heretofore unknown relationships in your data. Since it uses built-in functions you can use it anywhere that you use SQL!

Db2 13 offers additional AI help delivering the ability to simplify building models, Natural Language Processing (NLP), and exploiting the speed of the IBM z16 for training and querying data.

IBM z16 Synergy

The next thing that has been highly-touted is that Db2 13 takes advantage of new capabilities delivered in the IBM z16 hardware.  The new Telum chip used by the z16 mainframe provides powerful AI capabilities that Db2 uses to bolster its AI capabilities (such as SQL Data Insights). And we have already touched on that in terms of speeding up training and querying data for AI.

Db2 for z/OS is unique in that it is the only major DBMS that is designed specifically for a single operating system (z/OS) and hardware platform (IBM Z). This enables IBM (the provider of the DBMS, O/S, and hardware) to take advantage of capabilities unique to the platform, because there is no worry about supporting other platforms.

One example of this unique synergy is the ability to improve sort performance using the SORTL instruction of the IBM Z15 and z16. Additionally, the IBM z16 System Recovery Boost can minimize downtime by speeding up the performance of Db2 for z/OS restart. 

But What About BAU?

OK, so there is new AI stuff and great synergy with the IBM Z, but what about the features and functionality that make it easier to keep up with Business As Usual (BUA)? You know, things like easier administration, better performance, and so on?

Good news! There are a plethora of great new capabilities and improvements in Db2 13 for z/OS. While I cannot adequately cover them in detail today, some examples include:

• The ability to convert back-and-forth between partition-by-growth and partition-by-range Db2 table spaces. 
• Support for more concurrent threads and open data sets, as well as improved storage conditions. 
• DDF storage relief.
• Real Time Statistics (RTS) improvements.
• Many improvements to IBM Db2 utility functionality.
• Security and compliance improvements, including integration to the IBM Z Security and Compliance Center.

Summary

The bottom line is that there is a new version of Db2 for z/OS that mainframe shops will need to learn and prepare for. As with any new Db2 version, it will be exciting to dig in and discover all of the new stuff that can help us do our jobs better... and improve our organization's efforts to use its data to improve business.

Keep checking back here as I will blog in more detail about the new capabilities of Db2 13 for z/OS over time... 

TCBs, SRBs, and Enclaves

Many Db2 DBAs first hear about Task Control Blocks (TCBs) and Service Request Blocks (SRBs) in an IBM performance class, but not everyone has taken one of those classes. And even for those who have, a refresher is probably in order.

At a high level, for mainframe z/OS programs code can execute in one of two modes: TCB mode, also known as task mode, or SRB mode. Most programs execute under the control of a task. Each thread is represented by a TCB. A program can exploit multiple processors if it is composed of multiple tasks, as most programs are.

An SRB is a control block that represents a routine that performs a particular function or service in a specified address space. SRBs are lightweight and efficient but are available only to supervisor state software. An SRB is similar to a TCB in that it identifies a unit of work to the system. But an SRB cannot “own” storage areas. SRB routines can obtain, reference, use, and free storage areas, but the areas must be owned by a TCB. SRB mode typically is used by operating system facilities and vendor programs to perform certain performance-critical functions.

In general, z/OS dispatches Db2 work in TCB mode if the request is local, or in SRB mode if the request is distributed. These parallel tasks are assigned the same importance as the originating address space. Of course, this is a gross generalization and as zIIPs have become ubiquitous more SRB mode work has been enabled (as only SRBs can run on the zIIP).

Preemptible enclaves are used to do the work on behalf of the originating TCB or SRB address space. Enclaves are grouped by common characteristics and service requests, and because they are preemptible, the z/OS dispatcher—and Workload Manager—can interrupt these tasks for more important ones. There are two types of preemptible SRBs: client SRBs and enclave SRBs.

If the Db2 request is distributed DRDA workload, then it will be executed in enclave SRBs. If the request is coming over a local connection, then it will be dispatched between TCBs, client SRBs, and in some cases enclave SRBs (such as for parallel queries and index maintenance).

What Is an Enclave?

An enclave is a construct that represents a transaction or unit of work. Enclaves are a method of managing mainframe transactions for non-traditional workloads. You can think of an enclave as an anchor point for resource accumulation regardless of where the transaction is executing.

With traditional workloads, it is relatively easy to map the resources consumed to the actual transaction doing the consumption. But with non-traditional workloads (such as web transactions, distributed processing, and so on) it can be more difficult because a transaction can span multiple platforms. Enclaves are used to overcome this difficulty by correlating closely to the end user’s view of the transaction.

So even though a non-traditional transaction can be composed of multiple “pieces” spanning many server address spaces, and can share those address spaces with other transactions, the enclave gives you more effective control over the non-traditional workload. 

Synopsis

Hopefully this short introduction to TCBs, SRBs, and Enclaves has been helpful. At least the next time you hear somebody use these terms you'll have some idea what they are talking about!

Moving from IMS to Db2?

As a Db2 consultant and regular blogger I often receive questions about technical things, but also on strategy and industry trends. I try to help but I always make it clear when answering that I cannot predict the future, only make educated guesses... So with that introduction out of the way, one of the regular questions that I get involves comparing IMS to Db2, or helping to determine if it makes sense to convert from IMS to Db2. Here is the text of a recent question that was posed to me:

"My customer is wondering about the possible advantages of converting his IMS DB/DC system to IMS DC/Db2. The application currently performs well with an internal response time of less than .5 seconds on average. Even with an arrival rate of 425 full-function transactions per second, the queue count rarely goes above 10. This system typically peaks at 12.5 million transactions per twelve-hour day against HDAM and HIDAM databases totaling close to 1 terabyte. The application itself is currently a bit over seven million lines of code. Can you comment on the relative cost vs. advantage of moving an existing application from IMS DB to Db2 along with relative CPU capacity requirements?"

Here is my response:

Well, the main advantages of converting from IMS/DB to Db2 would be the better support for ad hoc query, support of standard SQL (instead of non-standard DL/1) for writing queries and a deeper pool of talent to support the Db2 environment. There are many more skilled Db2 developers out there than there are IMS techies these days. 

The primary benefit of sticking with IMS is the good and predictable performance you currently enjoy. And, of course, there would be no need to convert the database structures or the more difficult-to-achieve rewriting the necessary application code.

So, the high-level metric to keep in mind as you make your decision comes down to this: a well-designed IMS application will perform very fast, perhaps faster than a well-designed Db2 application (but that does not mean that Db2 is slow). On the other hand, it will be easier to develop applications for Db2, especially when data needs to be accessed multiple ways and in an ad hoc manner. 

I guess it boils down to this: How happy are you with the current application, are you able to support it properly and how many other IMS/DB databases do you support? If this is the last IMS/DB database and you are looking to convert away in order to rid yourself of the IMS license, then it makes sense to consider converting. But you should do a project plan and cost/benefit analysis before making your final decision (conversion can be very costly). If you have a lot of other IMS/DB databases, then don't convert to Db2 unless you cannot support the needs of your end users (management, ad hoc support, etc.) using IMS.

In terms of CPU requirements, Db2 will consume more CPU than IMS. Db2 optimizes queries internally whereas IMS programmers construct access paths to data. This additional requirement will cause Db2 to consume more CPU. But, of course, that additional CPU brings with it the enormous benefit of database optimization and better ad hoc query support.

Furthermore, if you do decide to convert from IMS to Db2, be sure to use Db2 as it was intended to be used. In other words, don't just convert segments to tables and be done. Make sure that you normalize your design and come up with a good "relational" Db2 database design. Also, be sure to train your programmers to write SQL queries. That means changing mindsets from the record-at-a-time processing of IMS to the group-at-a-time processing of Db2 and SQL.

For example, if you have master file processing logic it needs to be re-examined in Db2. Instead of open file, read record from file, use key to read record from database... you should be joining tables and reading from the join. This requires a different mindset and coding technique. 

As an additional consideration, keep in mind that Db2 is a much "newer" database technology than the hierarchical infrastructure used by IMS. So it stands to reason that newer capabilities and features will likely be implemented in Db2 before they are implemented in IMS; for example, AI and machine learning capabilities. That does not mean that IMS is obsolete, it isn't; IBM still maintains and upgrades IMS (at the time of writing, the current version is IMS 15.2 which was released for GA in March 2020).

Summary

Of course, this answer has been necessarily brief. I encourage you to read up on Db2 and understand its many differences with regard to IMS before jumping into a "go"/"no go" decision. Best of luck...

Wishing Z Mainframe a Happy Birthday

Today, April 7, 2022, the IBM mainframe officially celebrates its 58th birthday. The IBM 360 was launched on April 7, 1964 and the world of enterprise computing has never been the same.

I'm old enough to remember in the early 1990s when Stewart Alsop of InfoWorld predicted the last mainframe would be unplugged on March 15, 1996. And ever since he made that woefully inaccurate prediction many think that the mainframe is no longer relevant. But they are wrong... Here we are, 26 years after that infamous predicted drop-dead date and the mainframe is still going strong! 

Mainframes are designed to be able to process a trillion web transactions a day with the capability to process 1.1 million transactions per second. And 70% of the Fortune 500 use mainframes!

To all of you diligent mainframe users out there, today is indeed a day to celebrate... another year has gone by, and mainframes are still here... running the world!