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Hello World on z/OS

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Re: Hello World on z/OS

#21

Post by dralley »

mattzito wrote: post #16

The mainframe infrastructure is both the core feature and showstopper bug of the platform. On the plus side, it has empowered countless core business applications to scale years, even decades, beyond their original development lifecycle. On the negative side, it has created a stagnant cult of mainframe “priests” who oversee a platform that most businesses would rather get rid of, if they could only figure out how. My…

One of my older coworkers told me that IBM used to have a travelling mainframe demo in the back of a truck. As part of this demo, they would start a big computation, and then reach into the mainframe and start pulling out RAM and entire CPUs straight from the sockets, while the thing kept right on computing.

Re: Hello World on z/OS

#22

Post by bunderbunder »

mattzito wrote: post #16

The mainframe infrastructure is both the core feature and showstopper bug of the platform. On the plus side, it has empowered countless core business applications to scale years, even decades, beyond their original development lifecycle. On the negative side, it has created a stagnant cult of mainframe “priests” who oversee a platform that most businesses would rather get rid of, if they could only figure out how. My…

I think that, within the context of that story, both directors are missing the deeper issue: A company's technology decisions aren't just about the final state, they're also about getting the project bootstrapped, and all the other technology decisions between that point and the final state. So it's not just that Facebook had already done it their way, it's that, along the way, they never had any realistic alternatives that led toward a mainframe solution.

Having never worked directly with a mainframe, I can't really speak to the reliability question. What I do know, though, is that I've spent my entire life living around PC hardware, working on PC hardware, etc, because that's the hardware that's designed to fit into my day-to-day life. So, if I have a new idea, and want to try it out, I'm going to reach for the hardware I already have, because it's basically free. Just like Mark Zuckerberg did.

And at that point, I'm already on a path that leads inexorably toward building the reliability into the software. There's simply never going to be any point at which it makes sense for me to scrap everything I have so far and do a complete rewrite for a different platform.

Re: Hello World on z/OS

#23

Post by bunderbunder »

dralley wrote: post #21
mattzito wrote: post #16

The mainframe infrastructure is both the core feature and showstopper bug of the platform. On the plus side, it has empowered countless core business applications to scale years, even decades, beyond their original development lifecycle. On the negative side, it has created a stagnant cult of mainframe “priests” who oversee a platform that most businesses would rather get rid of, if they could only figure out how. My…

One of my older coworkers told me that IBM used to have a travelling mainframe demo in the back of a truck. As part of this demo, they would start a big computation, and then reach into the mainframe and start pulling out RAM and entire CPUs straight from the sockets, while the thing kept right on computing.

FWIW, you could do the same thing with a Spark cluster. It might not handle it quite as gracefully, since you'd be taking down entire compute nodes, and probably some of the data storage along with them, but the computation would also be able to continue.

Re: Hello World on z/OS

#24

Post by voidmain0001 »

nailer wrote: post #2

I demember doing virtualisation/containerisation for Linux on various platforms (including s/390 and z/VM but also VMware and Xen) at IBM. No matter what the platform was, the PMs would refer to the VM/container as an 'LPAR' (logical partition). Fun times.

Me too! I setup a couple of Linux LPAR on AS/400 - iSeries running OS/400. The distro was RedHat for PowerPC. One LPAR was for a Linux/Apache/PHP stack that used the DB2/400 database on the iSeries, and the other was to host an Oracle 8i instance. DB2/400 was a great RDBMS but there was an application requirement for an Oracle database, so the director of IT at the time said that if a DB is required then it must go on the iSeries since it hosts the primary DB the company used. I didn't care for his rationale, I just thought it was fun to be working with LPAR on the iSeries.

Re: Hello World on z/OS

#25

Post by dralley »

bunderbunder wrote: post #23
dralley wrote: post #21

Earlier quoted context omitted.

One of my older coworkers told me that IBM used to have a travelling mainframe demo in the back of a truck. As part of this demo, they would start a big computation, and then reach into the mainframe and start pulling out RAM and entire CPUs straight from the sockets, while the thing kept right on computing.

FWIW, you could do the same thing with a Spark cluster. It might not handle it quite as gracefully, since you'd be taking down entire compute nodes, and probably some of the data storage along with them, but the computation would also be able to continue.

Yes, but I'm guessing this predates Spark by decades. Not sure of the exact timeframe, though.

In any case, it helps explain why a purse-string-holding exec would be convinced to shell out money to IBM.

Re: Hello World on z/OS

#26

Post by voidmain0001 »

tony-allan wrote: post #12
api wrote: post #6

Earlier quoted context omitted.

They're not interested in anyone but people willing to write million dollar plus checks using their products. Those same giant customers have large legacy investments and plenty of money to hire teams of people to deal with things that are hard to use. Those kinds of customers care much more about things working for 30+ years without downtime than they care about UX. There's a whole world of solid, reliable, but unbe…

Sure z/OS is boring if your job is to write Cobol programs but if you are interested in sophisticated operating systems packed with very smart algorithms then it's a different matter. You can read about amazing hardware and IBM's ability to fuse hardware, microcode and software capabilities that keep pushing the ability to solve business problems. Yes, most of this is needed to extract value out of incredibly expensi…

Agreed! How could anyone consider Tandem Nonstop[1] boring when it let you rip and replace RAM, and CPU, etc on the fly with no downtime. Fun, fun!

[1] https://en.wikipedia.org/wiki/NonStop_(server_computers)

Re: Hello World on z/OS

#27

Post by Softly »

Missed my favourite part of learning the mainframe: where the enter key is.

Return and enter and two different keys, but, on most modern systems, they perform a similar function. On z/OS Return moves down a line (similar to Tab, but ignoring all entries on the current line) and Enter actually sends to data off.

Once you get used to it, it's really no different to the Linux or Windows command lines. It's certainly dated, but that's what you get from running a system designed to be fully backwards compatible (with 24-bit, 31-bit and 64-bit addressing modes) that can continue to run software that's over 40 years old.

[For reference, the mainframe originally had 24-bit addressing. When IBM wanted to add 32-bit addressing, they found that people had been using the remaining byte to store other data, such as flags. So, to avoid breaking customer applications, the 32nd bit is used to identify whether the address is 24-bits or 31-bits]

((And yes, for the record, I am an IBMer, working in a z/OS product that's over 40 years old))

Re: Hello World on z/OS

#28

Post by CuriousCosmic »

AnIdiotOnTheNet wrote: post #14

> IBM uses special and completely unintuitive names for basic concepts…. because OF COURSE THEY DO. As I recall, it's called "Bluespeak", and that sort of thing is pretty common actually. I was educated in networking at a Cisco netacad, so I use Cisco terminology that is apparently not universal. Programming languages do this too for some reason: Sum type, tagged union, discriminated union, variant...

I would argue with programming languages that it's less bluespeak-esque and rather that they have a more or less one-to-one relation with the mathematical principles they are based on.

Often programming features end up with a math name (matching the element they are based on) and a developer friendly name which in some ways makes life easier (by separating high/low level discussions) and more confusing (everything now has different names which get used based on author/speaker preference).

Re: Hello World on z/OS

#29

Post by mschaef »

wolfgke wrote: post #11
userbinator wrote: post #4

The reason why things are the way they are on mainframes, and how you should think intuitively, becomes a lot clearer once you realise that they are a long-evolved version of the very first mechanical punched-card processors: https://en.wikipedia.org/wiki/Unit_record_equipment In fact, I'm almost willing to bet that the foreignness of mainframes to the average developer is due to mini/microcomputers having become dom…

> Linux and DOS/Windows have far more in common with each other than mainframe OSes, despite their huge differences, because they evolved from mini/microcomputers and UNIX. Surely Linux and the Windows NT line (don't confuse the Windows 9x line, which evolved indirectly from DOS with the Windows NT line) have much more in common with each other than mainframe OSes, but Windows did not evolve from UNIX: The Windows 9x…

> The Windows 9x line evolved indirectly from DOS

Not sure what you believe to be 'indirect' about that relationship. That Windows codebase started out running on DOS and ultimately wound up so closely coupled that they shipped together in the same box as the same product.

> Windows did not evolve from UNIX:

Windows, through its DOS lineage, does indeed have some roots in the Unix tradition. (This should be unsurprising, since Microsoft was one of the more successful Unix licensees in the early 80's.)

https://blogs.msdn.microsoft.com/larryosterman/2005/06/24/wh...

To put Cutler's dislike of Unix into perspective, DOS (and Windows) had close to a decade of development prior to his involvement. (DOS shipped in 81, Cutler got involved in ~88, his first product shipped in ~93, and the old DOS-based Windows wasn't fully deprecated until 2001-1.)

Re: Hello World on z/OS

#30

Post by mschaef »

wereHamster wrote: post #5
userbinator wrote: post #4

The reason why things are the way they are on mainframes, and how you should think intuitively, becomes a lot clearer once you realise that they are a long-evolved version of the very first mechanical punched-card processors: https://en.wikipedia.org/wiki/Unit_record_equipment In fact, I'm almost willing to bet that the foreignness of mainframes to the average developer is due to mini/microcomputers having become dom…

Sure, that's certainly important to keep in mind. But that doesn't mean IBM shouldn't invest in usability.

> that doesn't mean IBM shouldn't invest in usability.

For whom? They shouldn't necessarily spend a bunch of effort adapting their product towards the Unix world, particularly to the extent it compromies their product for their primary customer base.

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