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Comment by cominous | Hacker News Reader

Is it just for the fun or is there actually a legit use case for having a mainframe at home apart from accelerating climate change?

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I think its a great career niche to be fluent in everything Mainframe, they are still used in critical places and will be for the foreseeable future and they are largely overlooked as a opportunity.

So if you want to work in this niche, having your own Mainframe will greatly speed up learning the system.

It probably also looks awesome when you market yourself.

So all in all, 25k USD for kickstarting a potentially very profitable career sounds like a bargain ....

I think we have very different definitions of "a bargain".

Hi, author here. Spot on! It is pretty common to see mainframe courses for $10k each - so given how much I hope to learn I kind of justify the cost just on that. Now, I do not expect to change to work on mainframes full time, but maybe it can grow into a side gig? Who knows! I do enjoy the process anyhow so it feels like a win-win :-).

Thanks for reading!

If you just want to learn the software, you can set up Hercules mainframe emulator for free. Finding an image of z/OS is left as an exercise to the reader, but won't take you long.

http://www.hercules-390.org/

For what it is worth, it will run using 100% renewable energy at https://datacenterlight.ch :-).

I'm not even sure if there are still use cases where companies use main frames for newly developed systems. Even core banking systems can be build without using a main frame.

If you Google around a bit, mainframes are pretty expensive, but have very high up times and other benefits.

Can't you get to that uptime with a well-configured cluster? I tried to find more information but couldn't find any other reasons why mainframes would still be the best option for a newly designed system?

IIRC the mainframe uptimes are for the cluster („sysplex”) anyway.

Author here, I might write a blog article about that because it is really quite interesting.

The TL;DR is that some might want to rather run 1 or 2 systems (mainframe) instead of 100 physical machines (conventional distributed cattle system).

Now, IBM does make it quite expensive but the mainframe has some pretty cool features like pay-for-what-you-use (which you of course get with the cloud, but not so much if you also want your data in-house).

Anyway, it is a fun beer topic if nothing else :-)

It does sound interesting, so please do.

Well...you sort of “pay for what you use”. I believe the extremely simplified version is you pay for the peak CPU usage (excluding specialty processors like ZIIP) in a moving 4 hour average window.

Context: I work for a large organization that used to run several physical Z13 mainframes, all of them containing several sysplexes. If we had issues, an IBM consultant would fly in within the day. We were definitely not IBM’s biggest customer but we were not insignificant for them either.

We had a lot of mainframe support staff (so not people programming for mainframe but people maintaining storage, DB2, z/OS upgrades etc.) and I think even for them, the IBM bill was more or less: we see a large number, no idea why it’s this amount, but we cannot prove it is not right, so I guess we’ll just pay it.

Mainframe billing is really complicated.

Also, with Mainframe, you’re not only using a different machine but also a different “everything”. You need specialized storage, you need to use an “exotic” programming language, you need people who know JCL, RACF, DB2 etc., for a lot of “middleware” (CD pipeline, access management, version control) you have limited vendors to choose from so you’ll pay a lot for that too. So if you are also running something else (Linux servers etc.) you basically need double the staff and licensing costs...

That is not really 100% true. You can certainly run z/OS if you want, and that incurs those costs you mentioned - but that is true if you want to run Windows as well for example.

However, the biggest thing to remember is that you can and should run Linux on these things as well. Linux on z, or zLinux as it for some reason is called, is just Linux on the redundant and fault tolerant mainframe hardware. Anyone with Linux experience could manage it really, and you would get a pretty damn good platform to build a high availability service on.

Good old days when I transit from XA to ESA, from dos/vse to movs, from racf administrator to dB admin, Ibm start to ship 3390-3, ispf, Rexx to generate jcl, patching and debug 370 assembler ...

Still holding a Hp dos pocket whilst working on all these.

ThOse were the days. Different very much from using a mac to run leela zero using egpu :-)

> Node.js on z/OS provides extra security and performance by leveraging the capabilities of IBM Z.

https://developer.ibm.com/mainframe/2018/01/19/reasons-host-...

The easiest of there has to be DB2.

Getting a cluster to guarantee that something happens excatly once is very hard, but doing things exactly once is an extremely useful property in banking. Using a single earthquake-proof computer with redundant everything, including hot-swappable RAM and CPU gives you similar reliability while making it much easier to achieve many desirable properties. Even if you can do the same in a cluster, spending more on hardware to reduce software complexity is worth it when bugs might cost you millions or billions of dollars.

Do you have a source on that new banks do not use mainframes? I'd love to learn what new banks use to talk to older banks.

From an EU perspective, most interbank communication for SEPA is through XML following PACS or CAMT xsd’s (so there’s a PACS format to transfer money, a CAMT format to inquire on the status of a payment etc.) sent via an intermediary clearing house. Used to be huge XML batches, but now moving to small XML messages.

Internationally also “MT” messages are used, which is also a file with specified format.

So it doesn’t really matter what stack you run, as long as it can create files and send them out :-)

Cool! Thanks for sharing! I have heard that some banks interconnect directly with IMS but I have no source for that.

check out https://monzo.com/blog/

I can't verify 100%, but I think Orange Bank (subsidiary of the telco provider) is entirely built on the cloud. I believe they built all their systems ground-up 2 years ago, but I could be wrong. When they acquired Groupama Banque, I think they basically started over on the systems.

Fun and learning.

I doubt there’s a legit use-case for a mainframe even in business environments. All the “reliability” it gives you can be re-implemented on commodity hardware and still come out ahead compared to the costs of buying & maintaining a mainframe.

I wonder how much cheaper it is to implement software for one, huge machine that „just works”, vs the usual way of implementing for a network of distributed machines. Distributed programming is NOT easy, and, even if the hard parts are supposedly implemented by various protocols/frameworks, these solutions constrain the way you can program and also have a ton of „interesting” failure states - just take a look at logs of say Hadoop cluster that’s been running for a while - even though the cluster is supposedly running fine (or is it?), you’ll find various kinds of exceptions related to the distributed model (socket timeouts and whatnot). Not to mention trying to thoroughly understand various eventual consistency models.

On th plus side, we’ve basically moved complexity from hardware to software (it was pioneered by Google, a software company, so no wonder) which increases salaries of software people, at the expense of hardware people. So yay for us I guess.

Author here, I agree 100%. It is just a different way of building software, which is why I find these things so interesting. It challenges my worldview and thus I want to learn more about its upsides and downsides.

CICS and IMS definitely made it easy to create scalable software decades ago. It is not that different from the frameworks we have invented to make distributed systems viable that you mention, which I find insanely cool.

One of the cool things of running e.g. Ceph is that it exposes a familiar API (POSIX filesystem) which makes things easy to integrate with. The mainframe is like that but for hardware. VMware has similar things to some degree where your VM can be kept alive across hardware failure, but not really on the same level.

Anyway, I will stop here but I could go on for hours :-)

> Anyway, I will stop here but I could go on for hours :-)

Oh please go on for hours; I'd love to hear more. Any format (blog or just semi-structured brain dumps in comment threads) will feed thoughts :-)

"I doubt there’s a legit use-case for a mainframe even in business environments"

You're incorrect. The most common one is to run legacy software, and not just banks. Insurance, retail, utilities, financial, manufacturing, etc. Some companies have been around before x86 hit the scene and already had significant investments in their in-house computing infrastructure.

Using a real mainframe in order to run legacy code is probably the most expensive way to do so I can think of.

Oh? Even when your environment uses z/OS, z/VM, CICS, DB2, and a whole slew of other IBM and 3rd party products? Do you know that all mainframe software is fully supported when run on a mainframe substitute? I have no idea whether it is or isn't.

He lists 'Datacenter setup' in his bill of materials at the end so it likely won't be kept at home.

I have my own "home server room" with a POWER6, but it's just a couple U in an extended tower. I can't imagine connecting this kind of a beast to household power, let alone getting it in the door. It takes a special kind of skill to maintain big iron like this and definitely the appropriate environment to house it.

Correct, it will run at https://datacenterlight.ch using 100% renewable energy. It the least I can do to offset the ~3 kW everything (z114 + dasd + everything else) will consume.

Is that a one off cost? Is there a yearly cost for keeping it in the datacenter?

There is recurring costs as well, something like $400/mo in power usage bills, and another $400 in internet and space rental fees per month. The folks over at the datacenter have been very happy to have me so there might be some discounts in there as well, but I am not sure. My goal was to keep the recurring cost as low as I can, and compared to what hosting a beast like this in a conventional datacenter would cost I'd like to think it's a pretty good deal.

Given that it generates like 10k BTU/hr or something like that the drain on the datacenter is non-trivial, so I a running cost was to be expected.

Can some crypto mining partially cover the recurring cost?

So, the M5 (M05) needed more power?

As somebody who started out in the 80s with Apple II and C64 stuff the year before going to college, I always laughed at the old “Star Trek’ episode where the new computer has to tap into the main engine for power. After seeing your new bit of kit, that doesn’t sound so far fetched :-)

Have fun with this beast.

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