W dniu 24.05.2023 o 11:03, David Crayford pisze:
On 21/5/2023 1:51 am, Tom Brennan wrote:
I'm not talking about 20 years ago.
You said, "Walmart used to have multiple mainframes"
Implication: They currently have only 1 or zero.
That's not the case, and I think you would be surprised at the count.
I can make an educated guess at two: one for production/development
purposes and another for disaster recovery. During my time in the 90s
at British Telecom, they were the largest mainframe customer in the
UK. They operated 32 data centers across the country, with an
impressive six located in London alone. The latest information I have
suggests that they now maintain two data centers in London
specifically for running legacy applications, one of them is a DR
machine. The billing system I used to work on has since been replaced.
Previously, they had a dedicated global billing unit that developed
custom systems. However, it seems they have transitioned to
off-the-shelf solutions capable of real-time billing, eliminating the
need for overnight batch processing.
Poland. The largest (almost the only one) national telecom. Early 90's -
several (17? 23?) companies ran billing system for the telecom. Various
systems, platforms, functionalities...
Late 90's - one billing systems, still several instances distributed
across the country.
~1999 - they started to build their own data centers. Not one, but 4 or
5. It had no real sense, but they did it. OK, they built 3 and started
fourth.
Then new owner decided to stop the madness and consolidate it. However
they decided to ...drop existing data centers and create yet another
one. In another city. They proposed employees to relocate few hundred
kilometers.
At the beginning single z/OS ran multiple instances of the billing system.
Then it was consolidated somehow, and sysplexed.
Then owner decided to get rid off the mainframe. To Oracle. The cost of
the project was approx. $100M
Then they had *almost* everything migrated. All but very large, very
profitable customers. Mainframe system was kept for years to support them.
Finally they closed mainframe. Few years earlier they started some
project to manage license costs which grew up exponentially. The costs
of new "open systems" solution.
BTW: How to report success after n-th missed deadline? They sold the
mainframe to external company and bought the service. SaaS.
Number of mainframe installations over the years: ~17 - 4 - 1 - 0
...plus a-lot-of-midrange-servers (hundreds, not dozens).
--
Radoslaw Skorupka
Lodz, Poland
----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
