What is Mainframe?
1) A Mainframe is also an large powerful-high speed computer which serves thousand of user connected to it. In todays world commercial use of computer is called as server. So mainframe is also a largest type of a server in todays use.
So from our Terminal means from out computer we are connecting to mainframe server for our business use.
So the mainframe server stores the critical data of much application for ex. Banking ,telecom,hospitality,travels,insurance etc. uses mainframes.
2) A mainframe is what a businesses use to host the commercial database-transaction servers-and application that requires high level security and 24*7 avaliable for their customer to use.
So for highly reliable and security purpose companies are using mainframe. Mainframe serves the entire domain.
EX. Imagine a bank server is a small server where the data resides. These servers never work when a large number of transaction took place where mainframe is exclusively good in transaction processing.Through Mainframe we can process million of record within a fraction of second.
ATM machine is also run on the mainframe so it is 24*7 avaliable. It is closed for only filling the money.
What about the space required for IBM mainframe server/computer?
At the start 1960 when ibm mainframe was developed it requires more space for its hardware device and for processor . starting around 1990 the size of processor and I-O peripheral is reduced.The size of mainframe server/computer is like a Refrigerator.
From 1960 there is only IBM mainframe why there is no competation
IBM never supplied an architecture of Mainframe the idea is only with IBM. From 1960 companies start using IBM mainframe for there mission critical application and now the situation is like that they cant replace the IBM mainframe. So they are keep using it as the cost of preparation is very high and there is no guarantee of success.
What is charges from IBM ?
As you submit the job means a unit of work to do on mainframe server then in the output log of job there is CPU time utilized for that particular work is counted on that Mainframe server which you are using. so it is like Electricity Bill how much you use you have to pay .
IBM charges a fee for the hardware, then they have software fees (one time charges and monthly recurring charges). Those costs, however, may or may not have anything to do with system usage. IBM will happily sell you a machine that sits idle, doing nothing -- but the price will (generally) be the same as for a machine that is 98% busy 98% of the time. IBM does have some usage-based pricing, but that's not typically directly based on CPU seconds if you installed in your own sites.
How user uses Mainframe computers/servers ?
Yes User can use access the mainframe computer/server from their desktop is called as terminal so location doesn’t matter you can access the mainframe from across the world.
Mainframe user interface is 80*24 character Green on black screen.
Many of todays web sites store their production database on mainframe host.
Important Features of using Mainframes.
1) Reliability -
AS mainframe is also a machine which made up of many hardware component so any hardware failure causes the impact on bussiness. So there is health checker which detects hardware failure problem early before any impact on business.
2) Availability-
The system can recover from failed hardware without impacting the running system.so the application is 24*7 avaliable.
3) Serviceability
When the hardware or software is failed it can be easily detected for replacement of hardware or software. So in that failure time also the application is available for service and during the less traffic on application the replacement is done.
4) Security
The critical data like bank account number-password-employee record is protected from unauthorized user . Mainframe computers has extensive capabilities to share the data among authorized user and protect the same.
So this important feature is of mainframe gives IT firm to use mainframe.
5) Scalability
It means that ability of hardware –software to continue the function well in any change.
Eg. If we add the processor or increase the memory then also application will perform good.
6) Extensibility
The system will continue come up with adding the new functionality into it to make it more reliable to use.Eg. Initially mainframe is used for batch processing so IBM introduced CICS for online programming.
What is Mainframe operating system (Z/OS) ?
I have doubt while I am reading the most of books-sides about operating system I came across two answers MVS (Multiple Virtual Storage) and Z-OS.
MVS and Z-OS is same only . IBM introduced MVS operating system in 1974 and modification of the operating system will reach upto Z-OS. So now it is Z-OS uses Mainframe computers .
Defination of Operating System
Operating System is nothing but a collection of programs which performs the system internal software-hardware –memory processor working.
So mainframe also having an operating system which manages its opearation this operating system is Z-OS.
Why IBM has introduced Z-OS ?
Early in mainframe the multiple user submits the job at a time then operating system takes one job at a time and gives the output to the requested user and then it takes the second job for execution and this process in continuing.
So By introducing Z-OS multiple job are executed at a time so no any queue problem.
Characteristics of Mainframe Operating System. . . .
1)Virtual Storage
Storage used by Mainframe operating system is Direct Access Storage Device (DASD) volume. In mainframe computer there is two types of storage one is Actual physical storagei.e memory and another is Virtual storage to which user has an access.z/OS keeps only the active portions of each program in central storage.
Virtual storage is a memory management technique by which programs are made to work as if they have more memory available to them than is actually attached to the computer. After running program on mainframe the output is reflect on physical memory or can be placed on disk.
2)Multiprogramming
It means simultaneous execution of more than one program in single CPU.So CPU utilization is better.
3) Spooling
As many user are submitting a job at a time so for the output of program given to printer which is shared among the user through spooling.
4) Multiprocessing
Two or more Central Processing Unit (CPU) shares access to main memory. So it removes particular CPU dependency as one CPU fails another CPU will take care of its work.
5) Time Sharing
In this each user hahrough a terminal devices access to the mainframe system. Here user interact directly with the mainframe computer.
I hope you understood the concepts in this tutorial.If you have any doubts regarding any of the topics discussed here, you can ask me on the comment section or drop me an email to akamble9488@gmail.com
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