“You do not really understand something unless you can explain it to your grandmother.” 
-Albert Einstein

Here’s my attempt to explain DB2 to my grandma!

With the world heading towards yottabyte of data, I assume that we all understand any raw, unorganized facts that needs further processing is data. We obtain data from numerous sources such as websites, retail stores and social media (this is a big one) to name a few. There is so much of user generated content off late that companies are struggling to:

  1. Manage the amount of data 
  2. Organize the data to gain intelligence 
  3. Make use of the information to gain business value.

How do we manage & organize data?

With all the data stored in databases, we need a Database Management System in place to create, maintain and control the databases on a regular basis. DB2 is a Database Management System and more specifically a Relational Database Management System. (RDBMS)

For those of you who are new to databases, here’s a list of top 5 reasons to use a Database Management System (DBMS):

  • It manages creating, accessing & managing data efficiently
  • It provides a greater level of security by granting different levels of security access based on the user
  • It allows multiple programs to access the data simultaneously while still keeping the data consistent (Data Integrity)
  • It permits the hiding of confidential data in separate views to prevent unauthorized access
  • It comes with a number of tools to perform activities like performance tuning, backup & recovery of data, implement tighter security controls and so on 

Fun facts about DB2

  • Top 59 banks in the world use DB2
  • 23 out of top 25 retailers use DB2
  • 9 out of top 10 insurance providers use DB2
  • IBM has over 1600 core developers and researchers for DB2 across the world
  • DB2 runs on many operating systems, such as z/OS, IBM i, Linux, UNIX, Windows, and Solaris 

You might be wondering why some of these large organizations use DB2 for z/OS to run their business. The answer is simple. These companies need a reliable database server which provides superior availability & scalability. These companies process huge (and I mean HUGE) volumes of information that would require millions of concurrent updates on a daily basis. DB2 with the power & functionalities of z/OS has undoubtedly met/exceeded those needs.

11 Things you need to know about DB2

  1. DB2 Data Sharing – DB2 data sharing runs on an IBM mainframe cluster configuration called a parallel sysplex and enables applications that run on more than one DB2 for z/OS subsystem to read from and write to the same set of data concurrently. Data Sharing gives businesses the ability to add new DB2 subsystems into a data sharing group, or cluster, as the need arises and without disruption which makes it the most highly available, highly scalable data-serving platform in the market. 
  2. IDAA – DB2 for z/OS offers IBM DB2 Analytics Accelerator (IDAA) which helps in excellent query performance solution for Data Warehousing and Analytics (Remember we talked about analyzing data to make sense out of it). 
  3. Application Portability – You can develop applications with SQL that are common across DB2 data servers and port them from one DB2 operating system to another with minimal modification. (Porting means moving an application from one operating system to another.) 
  4. Temporal Data – Many IT systems need to keep some form of historical information for their data and it is now possible with the latest version of DB2 which supports temporal data (Business time & System Time). With the use of a history table DB2 can now provide a value of data at a specific time in history. 
  5. Built-in Compression – DB2 has inbuilt compression technology which converts your data that is used frequently into shorter strings for efficient storage & retrieval. The mapping information of short strings with the actual data is stored in a compression dictionary which is used for decompressing the data. 
  6. Built-in Encryption – DB2 provides built-in data encryption and decryption functions that you can use to encrypt sensitive data, such as credit card numbers and medical record numbers. You can encrypt data at the column or value level. 
  7. Clone Tables – you can clone tables in DB2 with the exact replica of your base table and you can switch between the clones easily. This is very critical for businesses who cannot tolerate any downtime since clone tables ensure superior availability. 
  8. Large Objects – DB2 has a unique capability of storing Large Objects (LOB) which would mean storing a picture or a text document as a single object in the database. 
  9. Storing XML – You can also store XML on your DB2 Database. It has in-built functions to convert the stored XML and return it as a DB2 table to your application. 
  10. DB2 Express C is a community Edition which is a no charge edition from IBM 
  11. DB2 Tools – DB2 comes with a set of tools that are broadly classified in the following six categories. You will be hearing more about some of the DB2 Tools in our future posts. 
    • Database Administration 
    • Utility Management 
    • Performance Management 
    • Recovery Management 
    • Replication Management 
    • Application Management 

Phew!! That’s enough DB2 for today. I enjoyed writing about DB2 on Z as much as you did reading. So the feeling is mutual here. One last thought! We at Millennial Mainframers are fairly new to the Z world and we are learning Z just as you are. You call the shots if you would like to hear about something in specific and we would be more than happy to step up to the plate. Come back and see us for more cool information on how Z rules the world always & forever! ~ Riya ~

About the Author

Sri (Riya) Shanmugam
MBA. Entrepreneurship, McCoy School of Business, Texas
B.Tech. I.T., Amrita School of Engineering, India

Riya is a Product Specialist at IBM by profession and a nerd by choice. She closely follows the start-up world, believes that Rome was not built in a day, loves technology, fashion, food, interior decor, Jazzercise, long weekends and oh, did we say Fashion?? Her new crush is her Canon SLR and she is extremely psyched about Z. She is a Sun Certified Java Programmer and has been involved in all parts of Software Development Life Cycle (SDLC) at Infosys, AMD, IBM and an Austin based start-up. Here’s how you find her on twitter. @RiyaKSri
Posted in Uncategorized.

As one of the fairly new members into the mainframe family, I originally had some hiccups understanding the basics of mainframes. And by basics, I mean the absolute basics. I wish there was someone who could tell me a story of how it all happened from start to present in the mainframe world. A dear friend and a mainframe enthusiast suggested I read a book and the book clearly solved the purpose.Hence, here is a top ten list of the coolest z/OS facts.

1.      z/OS is an awesome multitasker

Back in the days, when z/OS was developed, computers were extremely expensive. Hence the developers built z/OS in such a way that different people could use z/OS to run multiple tasks at the same time. Every task that runs on z/OS runs in an address space and each task thinks that it’s the only one running. However, behind the screen, z/OS shares resources like memory and CPU across all tasks and there could be numerous tasks running at the same time sharing these resources.

2.      z/OS handles large workloads

It sounds quite obvious that z/OS can handle large workloads. But there must be a way to decide what tasks to run first and what can wait. In other words, how do we prioritize? z/OS uses a feature called WorkLoad Manager which helps in prioritizing system, production and non-production tasks. This helps z/OS in handling large workloads making 100% use of the CPU.

3.     It’s unbelievably hard to crash z/OS

Everyone expects z/OS to keep running and running and running. So anytime when a task crashes, we can not let that crash any other part of the system. Now remember we mentioned that every task runs in its own address space. So IBM has invested a lot of time and money in making sure that when a task crashes in one address space, it does not interfere with the normal functionality of the entire system, in other words making it robust and also clean up completely where the crash occurred so we can be up and running like new. But z/OS records any crash that occurs due to a hardware or software failure, so we can get into investigation later.

4.      z/OS has the best recording

z/OS comes with its own inbuilt scribe and we call it the System Management Facility(SMF). SMF records quite a lot of information like when was the system started, what task is currently running, when was a file created, when was it last edited, who deleted it, etc,. Security audits, capacity planning and performance monitoring are some of the uses of all this information that is recorded using SMF. IBM can proudly claim that z/OS has the most extensive recording of any operating systems.

5.     You need a job entry subsystem for z/OS

z/OS can run a series of jobs at the same time without any human intervention and they are called batch jobs. Users use a language called Job Control Language (JCL) to specify instructions for a specific job or a batch job to run. Once z/OS receives instructions from a user in the form of JCL, the role of a Job Entry Subsystem (JES) is to convert the JCL instructions into machine readable form and then queues them for processing, create address spaces, make sure all the input files for the job are ready, specify where the output has to be written and any other information required to run that job. Overall, JES acts like a manager, making sure, everyone has their resources to do their job and everyone does their job diligently.

  6.      How different are z/OS files?

                   We all know about files on windows. They store our data and we can access our files through an application like notepad. In z/OS, the concept of files is quite different. In the first place, they are not even called files. They are called Datasets. Each dataset is made up of records. When you create a new dataset, you need to specify the length of each record. Some other basic information that you need to specify are where the dataset should be stored and how big of a dataset it is. We will discuss about creating datasets and all the information you need to know to create a dataset in a later post. Hang in there!

               7.      How do you talk to the Mainframes?


How do we interact with such humongous mainframe computers and z/OS? We have to use an application called TSO/E( Time Sharing Option Extended) to talk to the z Systems. TSO/E is very hard to use. So z/OS comes with ISPF (Interactive System Productivity Facility). ISPF gives an interactive and easier way to communicate by providing lot of inbuilt functionalities

8.     You get UNIX with z/OS

When we say, you get UNIX with z/OS, that’s really an eye wash. What you really get is a POSIX compliant UNIX Shell called UNIX Systems services (USS). Posix compliant means that we meet all requirements to call it UNIX, but it’s actually not UNIX. 

9.      z/OS has a console

In your mainframe server room, you will have operators who would monitor your system on a regular basis to make sure if the system is running without any interruptions. The way they do it is, by monitoring the console with the system news feed to see what is going on in the system, if there are any alert messages or if there is any problem that they need to be aware of. The main z/OS console is directly plugged into the mainframe, so that even if there are network issues, the console will continue to work.

10.     z/OS isn’t enough

Once we successfully setup z/OS, we now have a basic operating system. But the real functionality of a mainframe is not exhibited unless we equip our system with applications that run on z/OS for security management, performance, database management, printing, etc,.  Apart from IBM, there are also other vendors in the market who sell applications that run on z/OS to make it more efficient.

If you need more of this, I suggest reading What On Earth is a Mainframe?
The book is a very easy read with topics ranging from fundamentals of mainframe hardware to application development on z/OS.
Posted in JCL.