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The IBM mainframe: How it runs and why it survives

arstechnica.com

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

#151

Post by sillywalk »

StillBored wrote: post #131

"Today’s IBM mainframe CPUs are based on a highly evolved version of the POWER architecture that IBM has been developing for over 30 years. " I've heard a lot of largely clueless people who weren't aware of the differences between the zeries and pseries say something like this, but its generally been entirely false (especially 15-30 years ago which overlaps with some time I myself spent at IBM). Given the rest of the…

I wonder if the article meant that IBM had worked on the POWER architecture for over 30 years? IBM did work on the eCLipz Project [0][1], combining / sharing tech from IBM Power/pseries, AS/400/iseries, and Zseries. This was around 2005-ish. I assume that collaboration has continued, but I don't know if that counts as 'based on ...'.

"The z10 processor was co-developed with and shares many design traits with the POWER6 processor, such as fabrication technology, logic design, execution unit, floating-point units, bus technology (GX bus) and pipeline design style, i.e., a high frequency, low latency, deep (14 stages in the z10), in-order pipeline.

However, the processors are quite dissimilar in other respects, such as cache hierarchy and coherency, SMP topology and protocol, and chip organization. The different ISAs result in very different cores – there are 894 unique z10 instructions, 75% of which are implemented entirely in hardware. The z/Architecture is a CISC architecture, backwards compatible to the IBM System/360 architecture from the 1960s. "[2] For the POWER

[0] https://www.realworldtech.com/eclipz/ [1] https://news.ycombinator.com/item?id=18494225 [2] https://en.wikipedia.org/wiki/IBM_z10

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

#152

Post by Scubabear68 »

neverartful wrote: post #144
Scubabear68 wrote: post #92

Earlier quoted context omitted.

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.

Call BS all you want, I don't care. I know what I witnessed. I don't know if the mainframes were owned are leased, but they were swapped out for new ones every few years.

I’d like to hear more then. Mainframes are traditionally a big investment where you consolidate tons of load and jobs and LPARs onto one honking big machine. A very expandable machine in terms of any resource you can think of.

Why would you turn over something like that every few years? Your narrative sounds more like taking about ephemeral cloud stuff, not multi million dollar main frames.

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

#153

Post by wkat4242 »

jjtheblunt wrote: post #137
hinkley wrote: post #85

Earlier quoted context omitted.

Most of this Cloud technology we like to go all atwitter about is a retread or a redesign of software that's been on mainframes for thirty years. The old farts must laugh themselves silly looking at us acting like we discovered a large white object orbiting the earth.

SUN used to say The Network is the Computer...that always reminds me of what is called "cloud" the last 10+ years.

Sun was way ahead of its time. Too far ahead in fact, in the sense that they brought products to market that the market didn't yet realize they wanted.

The Javastation network computer for example, it was a bit like a Chromebook (though incredibly slow -lol)

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

#154

Post by wkat4242 »

Solvency wrote: post #96
sofixa wrote: post #59

Earlier quoted context omitted.

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...

They are super wanted but it's true that it's very hard to get into.

Want to learn Windows, Linux, cloud whatever? Just build a cheap home lab and play to your heart's content. Because really, training is not how you get good. Nor is certification. It's the hands on experience that comes from running into the crap the vendor doesn't want to tell you. All the little annoying flaws they keep out of the documentation under pressure from marketing.

Good luck doing that with a system Z. Try to find one on eBay for peanuts the way you can get a nice ESXi server.

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

#156

Post by wkat4242 »

grishka wrote: post #66

> Communication is through Kafka events or Java Messaging Services, and new server instances can be spun up in seconds in AWS or Azure clouds to provide additional capacity, which is needed for high-volume processing. I'm honestly surprised that a bank would agree to run anything even remotely serious on someone else's infrastructure.

Me too. We sold a lot of dedicated fiber to banks in the early 2000s because they feared the packet switched nature of ATM. They thought packets would randomly end up at competitors.

I don't know if they ever realized even dedicated fiber links were software switched by that time so it was easy to misclick and send an entire fiber stream to their competitor too :)

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

#157

Post by ancantus »

hinkley wrote: post #125
queuebert wrote: post #108

Earlier quoted context omitted.

I posit that most tech companies make money by poorly recreating old technologies for use by younger people ignorant of the old ones. E.g. how many variants of IRC have we had now? Usenet? VMs?

I think we need history classes in programming, and possibly comparative literature classes but for code.

Some places have them. I took an elective class at university which focused on open source philosophy & licenses. Read and discussed a bunch of papers written by the guys involved in the early open source movement. Stopped short of code review though: which would have been a nice addition.

A very very good paper, and one that was clearly a passion project for the prof.

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

#158

Post by wkat4242 »

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.

Most companies are actively trying to exchange capex for opex though - even if it's way more expensive over the lifetime of the equipment or service.

It's that ultra short term results focus that the stock market demands these days, sadly.

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

#159

Post by mikewarot »

Absolute fringe opinion(or is it?): The performance and reliability are awesome, but have nothing to do with the real reasons IBM mainframes are still around.

Backward compatibility helps - you can still run code for the IBM 1401 on these machines if you need to. When they came up with System 360, they effectively crystalized software development... taking what used to be a forced march to new hardware every few years as you got a new, faster, incompatible machine, and were rewriting the code for the better faster hardware.... and just FROZE that stream of development, which is why Y2K really happened.

But even that's not the real reason IBM mainframes have stuck around so long... it's the same reason Virtualization and Containers took off.... they give no default access to files or disks, the administrator has to plan out which disks and other resources a Job, (or Runtime, VM, or container) will access. (Example, the DD statement of JCL[1])

This has the effect of being a very course grained capability object system.[2]

The default access to everything on a Windows/Unix/Linux system just doesn't work in the modern era. It is because side effects can be strictly controlled, that Mainframes and later VMs and Containers have so much value.

-- a small rant:

It's 2023... consider the humble AC wall outlet, you can plug almost anything into it, and the circuit breaker or fuse will prevent bad things from happening to your wiring, house, etc.

Why can't we protect against a rogue device plugged into a USB port? Why can't we just run any program we please, like we can plug in a lamp we bought at a garage sale, without risking everything?

--

[1] https://www.ibm.com/docs/en/zos-basic-skills?topic=concepts-...

[2] https://en.wikipedia.org/wiki/Capability-based_security

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