Traditional File System -

In the initial days of the Mainframe, IBM developed the file system concept to store, transfer, and accessing the data.

It is a traditional approach and can be effective only when the data size is small.

The traditional file system also has its advantages and disadvantages.

Advantages -

  • Accessing is fast if the file size is small.
  • Easily sharable within Mainframe Systems, including batch and online.

Disadvantages -

  • Accessing is slow if the file size is large.
  • A physical record can't be understood unless mapped with a copybook.
  • One process has to wait until the completion of another process is using the file.
  • No data recovery.
  • Data is not secured. Anyone in the group can access it if they know the file name.

Why DB2?

As discussed above, the file system can work efficiently when the file has fewer records or having less record size.

If the record size is large or the data is vast, then working with a file system takes more time than usual. It increases the cost to the companies using the Mainframe file system.

So, the Mainframe system has to have a new technology, platform-specific product to store the vast data with faster access.

IBM thought of implementing the relational database concept on the Mainframe system (Z/oS).

However, the Mainframe system needs a highly reliable, secured database structure used to store, analyze, and retrieve the data efficiently.

So, IBM came up with a product called DB2 for Z/oS that is more secured, reliable, and efficient.

What is DB2?

DB2 is a set of data management products that includes database servers. DB2 is a database product introduced by IBM.

DB2 was developed to store, analyze and retrieve the data efficiently. DB2 maintains the storage of large arrays of data types and optimizes the retrieval of that data.

DB2 was developed with the standard concepts of the SQL (standard query language) on relational database systems. i.e., DB2 uses SQL queries to store, retrieve the data from the database.

DB2 runs on IBM Mainframe, AS/400, and personal computers.

History -

  • In 1974, the IBM San Jose Research center developed a relational DBMS to handle the relational databases and System R with the main concept of Structured Query Language (SQL) to manipulate the database.
  • Database Management System or DBMS was named DB2 (IBM Database 2) in 1983 when IBM released DB2 on its MVS mainframe platform.
  • From there, DB2 as full-functions of DBMS was only available on IBM Mainframes.
  • Later, DB2 was available to many operating systems along with IBM Mainframes.
  • IBM developed DB2 by adding many features to each version, and the current stable version is DB2 12 for Z/oS.

Advantages -

  • Understanding the data in the tables is very easy compared to the other data management methods; hence, it has predefined attribute names. So anyone can able to understand very easily by relating the data.
  • Accessing is significantly faster.
  • Security is very high.
  • Independency is very high. For example, adding the new attributes is only required to create the DCLGEN sufficient. No other changes are needed apart from that.
  • Concurrency is very high. So that many applications/users can able to access the data concurrently.
  • Redundancy is significantly low.
  • It provides ease of access, and the user does not require to know the physical relationships of the database they are accessing.
  • Allows flexibility in design.
  • Reliable, secure, and high availability.
  • Handles large volumes of data with ease.
  • Works under different operating systems.

Disadvantages -

  • Licensing is a bit expensive, and support is paid.
  • Cannot create tables that can exceed the block size of the tablespace.
  • High consumption of mainframe processors.
  • Issue resolution or debugging an issue is difficult.

Differences between File System and Database -

File SystemDatabase
Understanding the data inside a file is very difficult since no column headings are present unless mapping with the copybook layout.Understanding the data inside a database is very easy since column names are present.
Access is slow.Access is faster.
Concurrency is very low.Concurrency is very high.
Security is very low.Security is very high.