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The IBM mainframe: How it runs and why it survives

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Re: The IBM mainframe: How it runs and why it survives

#91

Post by hinkley »

rob74 wrote: post #5

> Mainframes descended directly from the technology of the first computers in the 1950s. Instead of being streamlined into low-cost desktop or server use, though, they evolved to handle massive data workloads. I think the first sentence is 100% correct, but the second one not so much: current desktops and servers (not to mention laptops, tablets, smartphones etc. etc.) evolved from the first microcomputers introduced…

Centralization versus distribution.

Each person has a box in which they are essentially the sole tenant, versus a big box that has to have a bunch of sophistication to handle multitenancy.

Re: The IBM mainframe: How it runs and why it survives

#92

Post by Scubabear68 »

neverartful wrote: post #90
Scubabear68 wrote: post #84

One of the reasons Mainframes continue to be used is depreciation. I know a few companies who love their mainframes because they are fully paid for and from a budget perspective they are seen as “free”. This can be very attractive compared to the never ending OpEx for running cloud computing.

Doesn't make sense to me. I believe that IBM has found the forced upgrade path for hardware/software like Apple has perfected. You may not be able to run old versions of IBM's software and still have it be supported by them. Same for the hardware. I don't think you would commonly find and old mainframe (the hardware) in operation. At the last place I worked that had mainframes, they would upgrade to new models every…

I call BS on this. I never heard of upgrading mainframes every 2-3 years. It makes no sense. Mainframes are huge investments meant to last a long time, it is not a PC you replace in a few years.

Re: The IBM mainframe: How it runs and why it survives

#93

Post by tristor »

Hikikomori wrote: post #41
lizknope wrote: post #34

I've never used or even seen a mainframe in 26 years in the tech industry. My brother in law works for a bank and basically the business runs on it. The hardware and software are certainly impressive but does anyone use a mainframe for a new project and not just upgrading or expanding an existing system? I'm in integrated circuit design and we have compute clusters with thousands of CPUs. For some jobs we use a singl…

You'll most likely find it in large companies that operated in the 60s or 70s that haven't switched to anything new, mostly because their core business runs on it. I know of two companies, and at least one still use it, had several summer jobs there. They make sheet metal rolls by flattening out train cart sized hunks of steel, and while the mainframe system didn't run the machines (operators and PLC handled that) it…

Oh, fun times. I've been on the other side of that business in my past life, where I had to "revive" a business critical program written in VB3 (yes for Windows 3.x) after a computer migration that was used to calculate the weight of an aluminum or steel coil/roll via its dimensions so it could be input into the PLC for the feeder mechanism at the beginning of a production line that did forming/extruding of metals.

So on one end mainframes, on the other ends software written for DOS and Windows 3.x still being used in (at the time the 2010s) to keep critical infrastructure for manufacturing running.

Re: The IBM mainframe: How it runs and why it survives

#94

Post by AlbertCory »

Believe it or not: I never worked on an IBM mainframe, except in college. It always seemed like the prejudices against it meant that, once you get into that world, you can't get out.

That said: what the business types like is the belief, whether it's true or not, that when you call IBM for service they're there before you hang up the phone.

Also, a long time ago at Oracle, I sat in probably the most boring meeting of my life: a group called MOSES, composed of sysadmins for Unix. Their complaint was that, supposedly, all mainframe sysadmins did things the exact same way, so if you hired a new one, there was no training. Whereas in Unix, everyone did things differently, so a new hire couldn't be productive right away.

Re: The IBM mainframe: How it runs and why it survives

#95

Post by Solvency »

Listen to this episode "Mainframes are still a big thing" — https://changelog.com/podcast/524.

tldr: This awesome professor has an amazing track record of getting seemingly "average joes" trained up for mainframe programming. Because of how uncool this process is perceived by the average SV developer, it's literally shunted off into the dark recesses of the world, despite it being an awesome jobs platform.

Re: The IBM mainframe: How it runs and why it survives

#96

Post by Solvency »

sofixa wrote: post #59
jmartrican wrote: post #12

Earlier quoted context omitted.

Before we even get to the costs of a migration, what is the reason for the migration?

Well, for one, lack of capable personnel. Nobody learns IBM Mainframes in school, and most jobs for them want experience. Furthermore, they're not sexy but boring, with paywalled docs and similar shitty "enterprise" techniques, making it so very few people actually want to or manage to learn them. And it's a dead end, career-wise (very few companies use them, so changing jobs isn't as easy as more widely used tech).…

Completely untrue. Listen to everything Cameron Seay has ever said about the subject. Mainframe programmers are wanted more than ever.

https://www.youtube.com/watch?v=hxxyORcU3Hs https://blog.share.org/Article/mainframe-visibility-ibm-cham...

Re: The IBM mainframe: How it runs and why it survives

#97

Post by pmontra »

wredue wrote: post #77
ElectricalUnion wrote: post #11

Earlier quoted context omitted.

> It persists in many places due to the deeply ingrained belief that, for one reason or another, it would be technically, practically, or economically impossible to migrate functionality off the mainframe. It is never technical or pratical reasons, always economic reasons. To use contemporary vocabulary, you "just" need to replicate a "multi tenant HA cloud environment" to migrate from a mainframe at great cost. > An…

>most of the business software that goes into said mainframe is in fact very simple and straightforward Yeah no. I worked on mainframe code for 15 years of the last 20 and can tell you that you’re wrong. Even reasonably simple business lines have cobbled together insane cobol, batch and cics screens that would make spaghetti blush. When you open up a 100,000 line batch program that’s just 1 of 30 cobol programs in th…

What happens when there are new requirements? An example, fiscal legislation changes and programs dealing with money have to adapt. Of course a way out is to lobby for changes that don't touch the software, but what happens when the software must be touched?

Re: The IBM mainframe: How it runs and why it survives

#98

Post by Yasuraka »

neverartful wrote: post #89
larrik wrote: post #79

I never worked on z/OS, but I did work on AS400 (Series I, or whatever it's called now). I think the main things missing is how much IBM really brings to the table here. > If one crashes or has to go down for maintenance, the other partitions are unaffected. Effectively, IBM often does that for you. The machine detects an issue, and calls IBM, who sends someone out (in my day it was immediately), and they fix it. The…

"using a dedicated stack of hardware and software owned by one company" advantage - one throat to choke disadvantage - they've got you by the balls when it comes time to pay the licensing and maintenance fees

One has to wonder if the most optimal throat-choking to ball-holding ratio can be modeled

Re: The IBM mainframe: How it runs and why it survives

#99

Post by ibiza »

stcroixx wrote: post #65
ibiza wrote: post #32

Earlier quoted context omitted.

Migrating a suite of programs written w/ COBOL, CICS, DB2 from z/OS to Linux is fairly straightforward. MicroFocus COBOL compiles IBM COBOL, DB2 runs on Linux or you can swap out another RDBMS. The CICS part requires a simple runtime easily implemented in C plus a new scanner to replace the calls in your programs. I was part of a 4 person team that knocked this out in under a year. 1,000's of mainframe programs runni…

What replaces JCL?

The env I helped set up was online only, no batch jobs. JCL is essentially a declarative shell language, so it's not that hard to map to Bourne shell et. al.

Re: The IBM mainframe: How it runs and why it survives

#100

Post by ibiza »

hermitdev wrote: post #68
ibiza wrote: post #32

Earlier quoted context omitted.

Migrating a suite of programs written w/ COBOL, CICS, DB2 from z/OS to Linux is fairly straightforward. MicroFocus COBOL compiles IBM COBOL, DB2 runs on Linux or you can swap out another RDBMS. The CICS part requires a simple runtime easily implemented in C plus a new scanner to replace the calls in your programs. I was part of a 4 person team that knocked this out in under a year. 1,000's of mainframe programs runni…

> DB2 runs on Linux The DBA's I interned with would yell at you for this claim. They'd say UDB runs on Linux, but DB2 only runs on z/OS. I worked with both DB2 & UDB during my internship 2 decades ago, and while largely compatible with core SQL functionality, that changed quickly after you got off the "normal" path. UDB was released at a much faster cadence, and if you developed to the latest features of UDB, you'd o…

Re DB2 vs UDB, thank you, it's been too long. Well done breaking DB2!

We actually targeted Oracle on Unix. Fortunately, the app developers never got too deep into DB2-isms, so it worked out fine.

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