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Why The Dinosaurs Won't Die
DaveAtFraud writes "Ace's Hardware has a nice introductory article to the animal that will not die: The Mainframe. Ever wonder why these things are still around and what makes them different from a PC or UNIX box? The article is IBM-centric so there's no discussion of say the CDC Cyber series but when most people don't even believe that mainframes exist anymore, what the hay, let's disabuse them of that notion first. Hopefully, the author will follow up with the additional promised articles that go into more technical detail but this is a good place to start. I wonder if they still make card readers, too?" This guide came out last month, but it's worth looking through, even just for the pictures.
I talk to people all the time who can't believe that mainframes are still essential to our info infrastructure. I'm going to start sending them to this site. Any other suggestions for good primers, especially ones this short and sweet?
I really liked this line in the section about modern IBM mainframe reliability:
Each CPU die contains two complete execution pipelines that execute each instruction simultaneously. If the results of the two pipelines are not identical, the CPU state is regressed, and the instruction retried. If the retry again fails, the original CPU state is saved, and a spare CPU is activated and loaded with the saved state data. This CPU now resumes the work that was being performed by the failed chip.
Try that with your dual-Xeon server!
Ever wonder why these things are still around
Mainframes aren't dinosaurs, and never were. They are the most advanced, most capable hardware available, and the proving ground for architectural innovations that eventually filter their way down into workstations (like using a crossbar switch instead of a primitive bus). Sun's dynamic systems domains, considered very advanced by the Unix world are still many years behind the mainframe LPARs, and Sysplex makes SunCluster look like a silly toy. User-mode Linux and Beowulf don't even come close.
Really, you should be asking why obsolete technologies such as the bus are still used in PCs, and why PC technology lags so far behind "real" computers.
IBM and others have demonstrated the ability of mainframes to act as virtual machines, using hardware monitor techniques a la VMWare, to simultaneously run thousands of copies of Linux, AIX, or other OSes. Because each OS is running ON TOP of virtualized hardware, the security is pretty much airtight, and it's just like having thousands of actual machines without dealing with the space, etc. issues.
This technology seems quite promising for data centers, etc, and will probably ensure the mainframe stays around for a long time to come.
There's 10 types of people in this world, those who understand binary and those who don't.
I used to do client/server programming at a health care provider that employed over 20,000 people. The few apps that used Oracle were completely insigificant - EVERYTHING was on the AS/400. And they had a lot of AS/400's. In fact, they were buying MORE AS/400's. They were even planning on spending millions of dollars on a few very large AS/400's to replace several of the smaller AS/400's.
Why in the world would they still be using something so ancient? Legacy, man. "Back in the day", they started using AS/400's, and since everything was running on them, they just kept getting more and more of them. I'm sure that they're not the only ones that keep pumping millions of dollars per year into "Big Blue"'s coffers just because the idea of switching over is too daunting.
Of course, at the company I presently work for, we've done all of our CGI programming in Perl. We haven't found any reason to switch to anything else, and likely never will - but even if we did, we still probably wouldn't. It's taken YEARS of our entire programming team working like feral weasels to produce the programming we have. Just picking it up and migrating would take at least as long. If you look at the number of programmers, taking 4 years of their time to reprogram everything would cost them nearly a million dollars. The scary part? A million bucks is NOTHING compared to the market share we'd lose if we just took 4 years off from improving our product.
Yeah, legacy has a lot more power than most people realize.
steve
Oh, you're not stuck, you're just unable to let go of the onion rings.
And from the article:
The total I/O throughput capacity of the current z900 mainframes is no less than 24GB (that's bytes, not bits) per second. I have not personally had the opportunity to benchmark the performance on these latest systems, but while theoretical numbers can sometimes be misleading, I wouldn't be at all surprised to see a z900 performing as many as 100,000 I/O operations per second.
Immovable object, irresistable force, anyone?
dominionrd.blogspot.com - Restaurants on
You've hit the nail on the head in your first line: "Huge quantities of data". A modern, bog-standard mainframe has 24 GigaBytes per second throughput, between CPU(s) and persistent storage
That's a lot.
Your CPU-RAM bus on your PC has less throughput (DDR-SDRAM 266 is CA. 2.1 GB/Sec), and your CPU-HD path (via DMA to RAM) is a not-very-funny-joke compared to it.
A cluster for similar throughput would hit the lightbulb problem (admin-monkeys running round swapping out burnt out PeeCees left-right-and-centre).
MAINFRAMES SHOVEL SO MUCH DATA IT'S NOT FUNNY.
And now Linux can run on them.
Be afraid.
People are still buying the new mainframes and AS/400s (which should be lobbed in) especially now they run Java and new technologies.
Why ? Because of the support staff you require to run one. Is Unix harder than Windows 2000 are the people cheaper ? With these beasts its a mute question because YOU WON'T EMPLOY A SYSTEMS ADMIN for your server. You will outsource all of that to IBM, and they will make sure it works.
My favourite on this is being in a place with around 20 mainframes and AS/400s who had been asked to consider standardising on Windows going forwards. The IT manager's challenge to the sales guy was "How often does your stuff fail?" to which the sales guys asked "well when was the last time you had an expensive maintaince job on these servers".
The reply was that 4 years previously an IBM engineer had called to arrange a time to visit to replace a disk from the server which might fail soon. 2 years before that one had phoned to arrange a time to replace a processor board which was not performing correctly.
2 incidents on 20 machines in 10 years.
They elected not to move to Windows for infrastructure.
Then along came Java and suddenly you can buy these ultra-reliable boxes to run all of your newest and brightest applications.
Unix might whup windows, but OS/390 is Lennox Lewis standing at the back of the room with Ali smiling while they watch the little boys fight.
An Eye for an Eye will make the whole world blind - Gandhi