Friday, December 19, 2014

Season's Greetings

Seasons Greetings

And a hearty "Hello!" to everybody out there... just a short post today to wish everybody a very happy holiday season.

This is the time of year when work starts winding down somewhat and people start to spend time with their families. Whether it is Christmas, Hannukah, Kwanza, or just celebrating the end of one year and the beginning of another, may you spend it peacefully, happily and among those you love.

This will be the final post of the year for this blog, but be sure to join me again next year - 2015 - as we continue to examine all aspects of everybody's favorite DBMS... IBM's DB2...

Monday, December 15, 2014

The Wizard of Userville and the DB2 Developer's Guide

Once upon a time there was a kingdom called Userville. The people in the kingdom were impatient and wanted to know everything about everything—they could never get enough information. Life was difficult and the people were unhappy because data was often lost, and even when it was available, it was often inaccurate and not easy to access.
The King decided to purchase DB2, an advanced tool for storing and retrieving data. With DB2 the Users could process their data and turn it into information. “This,” he thought, “should keep the people happy. DB2 will solve all my problems.” But he soon found out that special knowledge was necessary to make DB2 work its wonders. Nobody in Userville knew how to use it properly.

Luckily, a grand Wizard living in a nearby kingdom knew many mystical secrets for retrieving data. These secrets were a form of magic called SQL. The King of Userville summoned the Wizard, offering him many great treasures if only he would help the poor Users in Userville.

The Wizard soon arrived, determined to please. Armed with nothing more than SQL and a smile, the Wizard strode to the terminal and uttered the magic words:

    FROM   DSN81010.DEPT  D,
           DSN81010.EMP   E

A crowd gathered and applauded as the desired information began pumping out of the terminal. “More, more,” shouted the data-starved masses. The Wizard gazed into the screen, and with amazing speed effortlessly produced report after report. The King was overheard to say, “You know, this is just too good to be true!” Everybody was happy. The Users had their share of information, the King had a peaceful kingdom, and the Wizard had his treasures and the respect of the Users.

For many months, the Users were satisfied with the magic of the great Wizard. Then, one day, the Wizard disappeared…in a jet to the West Coast for 150 grand a year—and a bunch of stock options. The people of the kingdom began to worry. “How will we survive without the magic of the Wizard? Will we have to live, once again, without our precious information?” The Wizard’s apprentice tried to silence the crowd by using his magic, but it wasn’t the same. The information was still there, but it wasn’t coming fast enough or as effortlessly. The apprentice was not yet as skilled as the great Wizard who had abandoned the kingdom. But, as luck would have it, one day he stumbled upon the great Wizard’s diary. He quickly absorbed every page and soon was invoking the Wizard’s magic words. And all was well again.

Well, life is not always that simple. Departing Wizards do not often leave behind documentation of their secrets. But...

Many of you who have purchased my book, DB2 Developer's Guide, will recognize the story recounted above because it starts the book off in Chapter 1. The idea being that the rest of the book is the Wizard's guide to DB2 for z/OS... 

If you use DB2 for z/OS for a living and you have never read DB2 Developer's Guide, maybe it is time to treat yourself to an early present for the holidays? The book comprises more than 1500 pages of in-depth DB2 knowledge and information. Over the course of 46 chapters DB2 Developer's Guide covers:
  • SQL Techniques, Tips, and Tricks
  • DB2 Application Development
  • DB2 In-Depth (an under the covers look)
  • DB2 Perfromance Monitoring
  • DB2 Utilities and Commands
  • DB2 Tools and Organizational Issues
  • Distributed DB2
  • and much, much more

The book has been in print for more than 20 years now and has been published in 6 different editions over that span. The current edition is the 6th edition published by IBM Press.

So continue and take the next step toward becoming a DB2 Wizard by getting your own copy today!

Wednesday, December 10, 2014

An Extra DBA Rule of Thumb

Last year on the blog I posted a series of 12 DBA Rules of Thumb. As a quick reminder, these Rules of Thumb - or ROTS, are some general rules of the road that apply to the management discipline of Database Administration that I have collected over the years. These ROTs are broadly applicable to all DBAs, even though this is a DB2-focused blog.

Please click on the link in the paragraph above if you need a refresher on the DBA ROTs from last year.

The purpose of today's blog post is to suggest an additional Rule of Thumb... and that is to Diversify!  A good DBA is a Jack-of-All-Trades. 

You can’t just master one thing and be successful in this day-and-age. The DBA maintains production, QA and test environments, monitors application development projects, attends strategy and design meetings, selects and evaluates new products, and connects legacy systems to the Web.
And if all of that is not enough, to add to the chaos, DBAs are expected to know everything about everything. From technical and business jargon to the latest management and technology fads and trends, the DBA is expected to be “in the know.” For example, the DBA must be up on trends like Big Data and Analytics.
And do not expect any private time: A DBA must be prepared for interruptions at any time to answer any type of question… and not just about databases, either.
When application problems occur, the database environment is frequently the first thing blamed. The database is “guilty until proven innocent.” And the DBA is expected to be there to fix things. That means the DBA is often forced to prove that the database is not the source of the problem. The DBA must know enough about all aspects of IT to track down errors and exonerate the DBMS and database structures he has designed. So he must be an expert in database technology, but also have semi-expert knowledge of the IT components with which the DBMS interacts: application programming languages, operating systems, network protocols and products, transaction processors, every type of computer hardware imaginable, and more. The need to understand such diverse elements makes the DBA a very valuable resource. It also makes the job interesting and challenging.
To summarize, the DBA must be a Jack-of-all-Trades... and a master of several!!!

Tuesday, December 02, 2014

DSN1COPY Improvements in DB2 11 for z/OS

There have been some nice data validation improvements made to the IBM DSN1COPY utility in DB2 11 for z/OS. I suppose I should first explain what the DSN1COPY utility is before I talk about how it has been improved, so...

DSN1COPY is also known as the "Offline Copy utility." It has many uses. Of course, the primary use case for DSN1COPY is to copy data sets without DB2 having to be up and running.  DSN1COPY can be used to copy VSAM data sets to sequential data sets, and vice versa. It also can copy VSAM data sets to other VSAM data sets and can copy sequential data sets to other sequential data sets. As such, DSN1COPY can be used to:
  • Create a sequential data set copy of a DB2 table space or index data set.
  • Create a sequential data set copy of another sequential data set copy produced by DSN1COPY.
  • Create a sequential data set copy of an image copy data set produced using the DB2 COPY utility, except for segmented table spaces. 
  • Restore a DB2 table space or index using a sequential data set produced by DSN1COPY.
  • Restore a DB2 table space using a full image copy data set produced using the DB2 COPY utility.
  • Move DB2 data sets from one disk to another.
  • Move a DB2 table space or index space from a smaller data set to a larger data set to eliminate extents. Or move a DB2 table space or index space from a larger data set to a smaller data set to eliminate wasted space.
DSN1COPY runs as a batch job, so it can run as an offline utility when the DB2 subsystem is inactive. It can run also when the DB2 subsystem is active, but the objects it operates on should be stopped to ensure that DSN1COPY creates valid output. DSN1COPY does not check to see whether an object is stopped before carrying out its task. DSN1COPY does not directly communicate with DB2.

performs a page-by-page copy. Therefore, you cannot use DSN1COPY to alter the structure of DB2 data sets. For example, you cannot copy a partitioned table space into a segmented table space.

Perhaps the nicest feature of  DSN1COPY is its ability to modify the internal object identifier stored in DB2 table space and index data sets, as well as in data sets produced by DSN1COPY and the DB2 COPY utility. When you specify the OBIDXLAT option, DSN1COPY reads a data set specified by the SYSXLAT DD statement. This data set lists source and target DBIDs, PSIDs or ISOBIDs, and OBIDs, thereby enabling you to modify these IDs accordingly (possibly for moving data from one subsystem to another).

You can also use DSN1COPY to  check the validity of table space and index pages. 

OK Then, But What's New?

So now that we understand the DSN1COPY utility, let's dig in to learn a little bit about how it has been improved in DB2 11 for z/OS. Basically, DB2 11 bring improved data validation to the DSN1COPY utility.

In DB2 11, the target data set produce by DSN1COPY is automatically validated after it is populated. The first time that the target data set is physically opened by an operation other than a utility, DB2 checks for inconsistencies in the data and the DB2 Catalog. The validation performed includes checking: 
  • DBID, PSID, and OBID
  • Table space type
  • Table schema (if the table space contains only one table)

If inconsistencies are found, DB2 throws a -904 SQLCODE and reports the issue. You can then use the REPAIR utility to remediate the reported issues. In past releases, validation did not occur immediately, which could have resulted in data corruption issues, storage overlays, and even ABENDs.


So you can rest easier knowing that DSN1COPY data is checked after it is created, thereby removing a lot of the chance for calamity if you ran the utility improperly... and that's a good thing!