CA-IDMSâ Underpins The Continuing Success Of BT Megasystem
by Bob Ratcliffe
BT is in a fiercely competitive business with around 200 licensed competitors vying for a share in the UK telecommunications marketplace. Market forecasts are that data, eBusiness, the Internet, multimedia, wholesale, mobility, and solutions will be double-digit growth areas, while fixed voice telecommunications will grow at only 3% a year. Quite simply, the company aims to become the world’s number one Internet company.
Much discussion of the demise of so-called legacy information systems has been not only premature but plain wrong and no better illustration exists than BT’s Customer Service System (CSS) at the heart of which are CA-IDMS databases. CSS is one of the largest and highest performing CA-IDMS installations in the world. It is the core operational support system for BT and generates a very significant proportion of BT’s income. CSS was built in the 1980s to overcome a number of problems that BT faced in providing excellent customer service. These covered such aspects as no integrated view of customer data—orders, faults, bills, and no end-to-end automation of provisioning. The system has been a phenomenal success as the statistics below show and investment continues in the development of new functionality.
First a flavor of the business—with 24 million customers and 28 million telephone exchange connections, and a need to print 610,000 payment requests with over two million detailed pages daily, size matters.
Now the technical stuff—running on the OS/390 platform the system comprises in excess of 1,900 online COBOL programs supporting 4,741 screens, and 1,680 COBOL and CA-Easytrieve® batch programs, a total of 9.6 million lines of code. Around 160 million transactions per day are handled by a mixture of CICS and CA-IDMS®/DC with a mean internal response time of 0.3 seconds. There are 29 separate images (LPARs) each hosting two CA-IDMS CVs, one for updates and one (in some cases two) for retrieval-only with database buffers synchronised by the Cogito product, DB-SYNCHRO. The current schema comprises 1,839 record names and 891 sets. Today the databases have 6.5 billion record occurrences deployed on seven terabytes of DASD with appropriate RAID protection, the equivalent of 2,500 volumes of 3390 model-3 logical volumes within integrated highly cached storage subsystems. Of course this all requires enormous computing power and CSS has outgrown the very largest ECL processors on the market. BT thoroughly tested CA-IDMS multi-tasking and proved it was a viable option, but with a 25% annual increase in transaction rates has opted to deploy vastly more powerful CMOS processors. CA-IDMS utilities together with partner products have enabled the DBAs to manage incredible growth in database size over the last decade and to exploit step changes in I/O subsystems and XA storage while also achieving manpower savings. The latter could not have been achieved without the separation of logical from physical database definitions in CA-IDMS Release 12.0.
Obviously enormous change has been required to build new complementary components and evolve the "legacy" in conjunction with other platforms and to respond to the deployment of client/server via reengineering activities. However, CSS will continue to grow, and CA-IDMS Release 14.1 Mixed Page Group support will certainly be required, as some of the databases exhaust available free page ranges from the 16 million available in those segments defined so many years ago with a maximum of 255 records per page. At the time of writing this article OS/390 Parallel Sysplex is being implemented and the CA-IDMS exploitation of this at Release 15.0 with multiple update CVs will inevitably need to be evaluated.
BT’s vision is to be at the heart of a society increasingly rich in communication and information, helping individuals, families, communities and organizations to interact, learn and flourish to the full. It is certain that this CSS system utilizing CA-IDMS software will have a significant part to play in the achievement of this vision.
Bob Ratcliffe, BT Information Systems Engineering, is the lead Operational DBA for the Customer Service System. Bob has 20 years DBMS experience, ten years as a user of CA-IDMS.