We are the IBM z/OS development team. AUA!

What language is z/OS written in?

Nearly all of them!

In all seriousness, because z/OS has such a rich history, it's written in many languages. Some of them include:

• C / C++
• Java
• z Systems Assembler
• UNIX shell
• REXX
• An internal language similar to PL/I.
• JavaScript / HTML

Why does WebSphere (on z/OS) come out with a buggy and not well-maintained OpenJPA implementation? JPA is one of the most important Java EE components. Why doesn't IBM invest more to at least reduce the gap between OpenJPA and Hibernate or EclipseLink?

The OpenJPA version inside WebSphere is carefully maintained to pick up required fixes without regressing existing behavior, especially in the service stream. So it depends on which version of WebSphere you are using.

WebSphere Liberty on z/OS uses OpenJPA for the jpa 2.0 feature, and EclipseLink for jpa-2.1.

If you have more specific questions, please let us know.

I will be joining IBM next month as a software developer for z Systems. I am very excited for this opportunity and I want to make the most of it right from the start. Do you have any recommendations what might give me a head start, both in terms of technical knowledge and business culture?

It depends on what product you'll be working on. I'd just be sure that you know about good software development practices, including source code control, using an IDE, collaborating with teammates, and similar things.

Mainframes are sometimes unfairly seen as a dinosaur technology. What are potential areas of growth for z/OS? What are some industries or services that are not using mainframes now, but could benefit from use of a z/OS mainframe?

There are a number of growth areas:

• serving data for analytics
• support for mobile transactions
• continued enhancements in security
• and much more!

What's something new in z/OS where I would say, "Yeah, I'm going to go ahead and move my platform there"? I'm sure there's plenty of things for existing customers, but why should I as a non-customer go to the platform?

The mainframe offers a tremendous amount of capability and value in the areas of availability, resiliency, and security. These are way more than "marketing" attributes. The capabilities are designed into our systems and significant development goes into QoS and driving service levels. There is a reason that banks, utilities, and airlines use z/OS, and it comes down to being able to bet their business on it.

For more details, you can check out the release announcement.

1. At what point (performance/size/reliability) does it make sense to ditch "normal" hardware/software and use z/OS?
2. What are the most/least fun parts of z/OS to work on?
3. How much maintenance do z/OS systems usually need?
4. Does turning it off and on again help?
5. What was the oldest bug you found while developing z/OS?

Well, the nice thing about z/OS is that it can run "normal" software as well. It can be straightforward to port a Java or UNIX application to z/OS, depending on how the application is constructed.

What does the group think after reading "Robert X. Cringely's" blog posting that you can find here?

We're readers of Bob Cringely's columns, and we find them interesting.

Can you describe a mainframe at a high level?

i.e., I presume it has more than one CPU and lots of RAM and hard drives, but it's not a collection of distinct servers running a clustering OS. Is it a single motherboard with hundreds of CPUs attached somehow? Is it the size of a server rack?

Please explain like I'm 15.

While conceptually computers work the same, two core things distinguish the mainframe. The hardware design is really a System design. Yes there are CPUs and RAM, but we have layers of CACHE memory, separate IO processors for disk and networking, and redundancy in design to ensure we survive failures of any component.
Then there is the software, designed for the highest levels of performance and integrity. Our clustering (Parallel Sysplex) and software is intended to prevent an application from going down and if it does trying to ensure data is never lost. We aren't perfect, but close :)

Additionally, a mainframe is designed to run at 100% utilization. If you try to run a regular system at that point, you might find that your applications aren't getting the response time that you expect.

I heard a story where a server room caught on fire and all the computers melted and burned but apparently the IBM Mainframe was running while on fire. Apparently they even managed to swap out the hardware with no down time.

Have you heard of such a story, is this even possible?

With parallel sysplex, absolutely. If you have your CECs spread across two rooms/floors in your data center, one room could fall into the ocean while the systems in the other room carried on without a hiccup. If you had everything on a single CEC, then things would get a bit dicey. But all of the hardware has redundancy built in, and is designed to be field replaceable.

We actually have a set of rooms on our test floor where we test the hardware against various environmental hazards, like earthquakes, extreme temperatures, static discharge, falling off a truck . . . I've never been able to witness such testing, but I'm told the folks that do do it really enjoy their job.

If you're wondering about what an earthquake test looks like, check out the video.

How does IBM stay competitive vs generic x86 architecture and server virtualization being the dominant force behind most environments currently? To be blunt, white box x86 systems are cheaper than dirt some times and a menagerie of applications for those systems are practically falling off the shelves, what helps you guys maintain your edge in the medium to large business market?

Well, a cheaper than dirt system doesn't have the reliability of a mainframe. Because they fail more often, more time is spent replacing faulty hardware, which requires more human management cost. Simply put, you can manage a mainframe with less people than a menagerie of white box systems.

As far as applications go, Linux on z Systems will run mostly whatever Linux application you want on it. It's supported by a number of distributions, and from a user perspective, feels just like any other Linux system.

Regarding the business market, we have a lot of customers that consolidate sprawling server farms onto just a few mainframes. When each one can run hundreds (or more!) of virtual machines, the savings starts adding up.

You're correct they don't have the up time, identical system builds and hardware virtualization generally is used to combat this with wide, memory dense clusters; DELL makes garbage, HP is nearing that same classification with driver/firmware issues in the DL series of hardware... and CISCO is possibly the front runner for best in breed of x86, but you pay for it...

As for expertise, with x86, server virtualization and *nix / Windows engineers being more prevalent and cheaper to train, what has IBM done in the last couple years to combat the retiring demographic of Admins/Engineers that have been around almost as long as the product?

P.S. Mass storage guy, generally interested as IBM products (Namely, the 'mainframe' and POWER systems) interest me and the architecture has always been viewed by myself as superior, just usually cost prohibitive from the upstart, annual support and cost of expertise. Working at a hospital; but what do I know, I'm just a storage/windows flunky ;)

Regarding the training aspect, you should check out some other responses in this thread. Things like the Master the Mainframe contest , Marist College classes, IBM Redbooks, zUniversity are some of the ways we're trying to combat the retiring mainframe demographic.

As far as storage goes, would you be interested in talking with one of our storage experts? I'm a software developer, so it's not my area of expertise, but I could certainly connect you with someone.

How common is it for customers to run Java EE on z/OS, e.g. via Liberty or WebSphere?

z/OS is a first-class platform for Java. The latest version of IBM Java 8 is available on z/OS.

What is the advantages comparing to Linux?

They are different - which is why we run both. Actually one of the great things about z Systems is the ability to run both together with integrated capabilities across both

OK, that is a very political answer :) - Yes, each has its own strength and weakness.

Can you point out how z/OS and Linux can work together, while they are running beside each other? Does z/OS learn from Linux and the other way around? And don't you think Parallel Sysplex is an outstanding feature compared to Linux with HA solutions, do you? :)

If you are a business that has investment in z/OS, with lots of line of business applications running there, but also has a number of Linux based applications running on a server farm, a mainframe can make a compelling solution. Depending on workload size, you might be able to put all your applications inside a single box, spread over a number of partitions (LPARs) This would reduce response time by keeping network traffic inside the box.

Is there a git client available for z/OS uss?

Not that I am aware of

I know for z/uss we are often using the filesystem and copies as a VCS. But IMHO it would be great to have a git client for admins stuff. Perhaps ibm is able to add a git client to ported tools (perhaps jgit runs on z)?

It looks like there were some attempts at porting it here. It doesn't look like it was ever completed though.

Are there any good posters showing the insides of the z13 (ie. like http://imgur.com/a/Z06xs) which I can hang on my wall?

Wow if that isn't the precursor to skynet... I don't know what is. Those insides are mostly showing raw cards, they're usually encased in metal. There probably isn't any material with the covers open unfortunately...

It's not a poster, but I have a picture of one of the demo machines with the insides all lit up.

Fun fact - the clock in the corner of the image is an IBM grandfather clock, and it used to sit in T. J. Watson Jr's office.

What's are the best ways for independent software vendors to get answers to z/OS related questions that can't be answered by reading IBM docs?

Join PartnerWorld and come to the Technical Disclosure meetings and calls! You can also ask questions in forums like IBM-MAIN and similar ones for TCP/IP, RACF, and z/OS UNIX, where a number of developers hang out.

You can subscribe to the IBM-MAIN mailing list here: https://listserv.ua.edu/archives/ibm-main.html

I actually did one of the mainframe challenge. It was the 2011 edition of this.

My general impression was that it was hard to access mainframe, everything there was arcane.

I have to say I still don't quite understand the lure of mainframe. Why do some people prefer mainframe over a cluster of server? Is there still a big market for mainframe?

A mainframe is essentially a cluster of servers, but all in one box. Depending on your workload size and type, you can end up with lower operating costs once you take into account datacenter space, power, and cooling costs. Buying racks of servers might be cheaper at the outset, but over time the mainframe wins due to the lower operating costs.

As far as being arcane, I'll agree that using ISPF and TSO are definitely different than what most developers are used to nowadays. However, if you're a Windows developer, would you consider Linux to be arcane? It all depends on your experience and what you're used to.

So if I want to try out mainframe or learn more about it, what's the cheapest and easiest way to go about doing it? I suppose I used the word arcane, because nobody else around me seem to use it.

There's a number of responses in this thread already, but in short, check out the existing Redbooks or pubs, or look at Marist College's online classes,

Hey, thanks for doing this! When will we see Linux System Services? (only partially kidding)

More to the point: How is z/OS addressing the need for DevOps in this new age of born-on-the-cloud software development methodologies?

For Devops we have initiatives in many of our middleware such as CICS and WAS which are all brought together with technology in Urbancode Deploy.

In all seriousness... what's the future of USS / Unix-like development on z/OS?

USS feels like it's falling behind, as it becomes more and more difficult to get build tooling up and running on USS (git, python, etc.)

Python is a tough one, as the ASCII/EBCDIC issue makes compatibility difficult.

Apparently it's available via Rocket Software. Thanks, /u/mainframe_kdm!

Someone in this thread suggested jgit runs on z/OS UNIX, but I haven't personally tried it.

What can I do, as someone who is interested in z/OS, has worked with it in the past (a little shy of a decade ago), and would love to continue to explore it and sharpen my skills?

My current employer has near zero interest in mainframe technology, so whatever I do must come out of my own pocket. I have no connection to any academic institutions which might be partnered with IBM.

I understand that there are things like zPDT which bring the cost down into the 4-digit USD range. Is that it? Of course, no one expects the cost of professional development to be free, but it seems that in the PC world, there are ways to cut your teeth on virtually any new technology without spending a lot of money up front.

Some universities offer classes on z/OS. Marist College in particular offers online classes in this area.

How to create custom modify commands? (so that WAS runs a jython script or mbean)?

I'm not sure what you mean here. Is this a WebSphere specific question? Or do you mean something else?

thoughts on ai?

Depends what you mean. "Ccognitive computing" is an increasingly important part of how businesses work. Looking at point of sale trends, fraud detection, etc. It's also where we are headed for how you manage the system.

For more about fraud, see our whitepaper on how an insurance company was able to perform real-time fraud detection on their claims process.

What are the long term plans for competing in an increasingly Linux/cloud dominated market?

Linux runs very well on a z System. z/OS was actually the first "cloud" environment. We also support hybrid cloud environments, and offer crypto "as a service".

Do you have any plans to market a lighter-weight (cheaper) version of RDz that's just for assembler development? Or maybe an a-la-carte RDz? I can't justify the cost (~$4000) knowing that a ton of the features aren't for me (e.g. COBOL, zUnit, etc). How much $ for just the syntax highlighting and control-click to DSECTS? :)

Why don't you check out IBM Explorer for z/OS?

I have several questions:

1. What portions of the OS were written in PL/X?
2. What portions were in C/C++?
3. WRT the C/C++ portions, were there any difficulties that would have been better handled by something like Ada? (Or did PL/X adequately cover those areas?)
4. /u/ahk99: what's the most challenging problem you tackled in optimizing COBOL?

Much of the base operating system code (memory management, scheduler, job control, etc) was written in PL/X, as C hadn't been invented yet :)

Much of the UNIX System Services code is in C. There is also the option to use Metal C to write code that directly interacts with z/OS system services.

Are you at all worried that zos will disrupt the time space continuum if you run it without an organoid?

No, but our latest mainframe model has a power level of over 9000!

Do you realise that it's because of you with z/OS, DB2 & Websphere that Oracle forked over billions for Sun? Just so they would own part of your enterprise stack.

Hehe... Larry... what a nutter...

Imagine an alternate universe where IBM bought Sun. What would the enterprise computing landscape look like nowadays?

Can I sign a contract with IBM to get 100% guaranteed hardware + software correctness (at a cost of 10M USD per mistake found) and 99.999% uptime (at a cost of 1M USD per minute of downtime above that)?

How much would it cost? If you cannot offer this, why would I care about IBM in the first place?

As far as uptime goes, a properly run parallel sysplex can achieve greater than five nines of availability. I've heard of customers with over a decade of uptime across a sysplex.

Why not go with Linux ?

You certainly can go with Linux on a z System! We give you the choice of RHEL or SLES, or you can even run Debian on it if you prefer.

z/OS also offers a UNIX environment, which is able to interface directly with traditional mainframe software.

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I'm confused by the question. z/OS and AIX are completely different operating systems, which run on different hardware platforms.