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I don't mean this in a condescending way at all, but really out of sheer curiosity: Who uses mainframes nowadays and what for? I find mainframes fascinating, b

• deleted 1y ago
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• tw04 1y ago
  Pretty much every fortune 500 that's been around for more than 30 years. Batch processing primarily - from closing their books to order processing, differs by company. But if you ask the right person, they'll tell you where it's at.
  • tgv 1y ago
    Fortune 500? More like Fortune 50000 (ok, exaggeration). But there are so many banks in the world, and their automation can run back to the 1950s. They are only slowly moving away from mainframes, if only because a rewrite of a complex system that nobody understands is tough, and possibly very costly if it is the key to billions of euros/dollars/...
    • justin66 1y ago
      That's all true, but these machines often run java code. That's something to contemplate.
      • rbanffy 1y ago
        IBM prices processors differently for running COBOL and Java - if you run mostly Java code, your monthly licensing fees will be vastly different. On boot, the service elements (their BMCs - on modern machines they are x86 boxes running Linux) loads microcode in accordance to a saved configuration - some CPUs will run z/OS, some will run z/OS and COBOL apps, some will run Java, some will run z/VM, some will run Linux. This is all configured on the computer whose job is to bring up the big metal (first the power, then the cooling, and only then, the compute). Under everything on the mainframe side is the PR/SM hypervisor, which is, IIRC, what manages LPARS (logical partitions, completely isolated environments sharing the same hardware). The cheapest licensing is Linux under a custom z/VM (they aren't called z but LinuxONE), and the most expensive is the ability to run z/OS and COBOL code. Running Java under z/OS is somewhat cheaper. Last time I saw it, it was very complicated.
• bronco21016 1y ago
  I understand that a company I work with uses a few, and is migrating away from them. It seems clear to me that prior to robust systems for orchestrating across multiple servers that you would install a mainframe to handle massive transactional workloads. What I can never seem to wrap my head around is if there are still applications out there in typical business settings where a massive machine like this is still a technical requirement of applications/processes or if it's just because the costs of switching are monumental. I'd love to understand as well!
  • rbanffy 1y ago
    Bank payment processing is the primary example - being able to tell if a specific transaction is or not fraudulent in less than 100 milliseconds - but there are other businesses with similar requirements. Healthcare is one of them, and fraud detection is getting a lot more sophisticated with the on-chip NPUs within the same latency constraints.
  • zifpanachr23 1y ago
    There are really applications that are large enough and hard enough to parallelize and/or shard that any rewrite on a different platform would turn into a performance catastrophe, even if you hired the best engineers and wrote the whole thing in very efficient C++, which you never hear about them doing because its usually only about saving money and so it's done with as cheap of developers as possible and in Java. I've seen it and it's not pretty. They tend to be dog slow and unresponsive, and even harder to maintain than the crusty old assembler and COBOL, because you have to implement a lot of the report writing and record crunching features built into a domain specific language like COBOL from scratch it you want to write the same application in Java. That's my biggest pet peeve with people that want to ditch mainframes, which is that they seem to care very little about the quality and performance of the software in my experience or they would only be thinking of replacing COBOL and Assembler code with an equivalently performant modern language and dialect. The desire to migrate is often driven primarily to have cheap, easily replaceable developers.
  • philjohn 1y ago
    IBM advertise 8 nines of reliability for the z17 (i.e. a second of downtime per year). If you have a workload that cannot go down it's going to be more reliable than orchestrating a bunch of cloud servers where you're dealing with the network, hosts going down, failing, or issues with errors in the CPU (yep ... happens at scale). They also test the hardware to exacting standards - 8.8 magnitude earthquake is one example.
• dragonwriter 1y ago
  > Who uses mainframes nowadays and what for? Large institutions (corporations, governments) that have existed more than a couple decades, and have large-scale mission-critical batch processes that run on them, where the core function is relatively consistent over time. Very few, if any, new processes are automated on mainframes most of these places, and even new requirements for the processes that depend on the mainframe may be built in other systems that process data before or after the mainframe workflows, but the cost and risk of replacing the well-known, finely-tuned-by-years of ironing out misbehavior, battle-tested systems often isn't warranted without some large scale requirements change that invalidates the basic premises of the system. So, they stay around.
  • strongpigeon 1y ago
    Thanks for that and yeah that fits with what I've found, mostly continuation of legacy, critical systems that were built on mainframes. It just seems shocking to me the amount of investments IBM still puts on developing those machines given that no one seems to want to use them anymore? It feels like I must be missing something, or maybe just underestimating how much money is involved in this legacy business.
    • reaperducer 1y ago
      given that no one seems to want to use them anymore According to a 2024 Forrester Research report, mainframe use is as large as it's ever been, and expected to continue to grow. Reasons include (not from the report) hardware reliability and scalability, and the ability to churn through crypto-style math in a fraction of the time/cost of cloud computing. Report is paywalled, but someone on HN might have a free link.
      • wmf 1y ago
        Those analyst reports are kind of bought and paid for by vendors BTW.
      • wstrange 1y ago
        Consider me skeptical. A mainframe has to be the least cost effective "crypto-style" math machine you could imagine.
• anonfordays 1y ago
  >Who uses mainframes nowadays and what for? Do you have a credit card? Do you bank in the USA? If you answered "yes" to either of the above questions, you interact indirectly with a mainframe.
  • strongpigeon 1y ago
    By that, do you mean banks, payment networks or both? And I guess I'd be curious as to why mainframes versus the rest. It seems like the answer for "why" is mainly because it started on mainframes and the cost of switching is really high, but I wonder if there isn't more to it. Edit: Oh yeah, just saw MasterCard has some job posting for IBM Mainframe/COBOL positions. Fascinating.
    • renewedrebecca 1y ago
      Both. Mainframes though are incredibly good for both I/O and uptime. Yeah, Linux/Unix are way better on both than they used to be, but on a mainframe, it's just a totally different level.
      • leeter 1y ago
        Not just that. Most operating systems lie about when an IO transaction completes for performance reasons. So if you lose power or the IO device dies you still think it succeeded. A mainframe doesn't do that... it also multiplexes the IO so it happens more than once so if one adapter fails it keeps going. The resiliency is the main use case in many situations. That said IME 99.995% of use cases don't need a mainframe. They just don't need to be that reliable if they can fail gracefully.
      • dralley 1y ago
        You can run Linux on mainframes fine. RHEL has first-class support for s390x / Z.
        • dardeaup 1y ago
          Yes! I had the good fortune of working with z/VM for Linux guests. It was a lot of fun and it worked quite well.
• reaperducer 1y ago
  From what I've read, 70% of the Fortune 500 do. Here's a brochure that might be useful to read: https://www.ibm.com/downloads/documents/us-en/107a02e95d48f841 https://www.ibm.com/downloads/documents/us-en/107a02e95d48f8... It's an IBM brochure, so naturally it's pumping mainframes, but it still has lots of interesting facts in it.
• sho_hn 1y ago
  > I don't mean this in a condescending way at all, but really out of sheer curiosity: Who uses mainframes nowadays and what for? There's probably some minor strategic relevance here. E.g. for the government which has some workloads (research labs, etc.) that suit these systems, it's probably a decent idea not to try and migrate over to differently-shaped compute just to keep this CPU IP and its dev teams alive at IBM, to make sure that the US stays capable of whipping up high-performance CPU core designs even if Intel/AMD/Apple falter.
  • dralley 1y ago
    Those customers don't use mainframe, they use POWER. There's been a handful of POWER supercomputers in the past decade built for essentially that reason.
    • rbanffy 1y ago
      POWER is not uncommon in HPC, but IBMi (which is very enterprisey) is also based on POWER. You won't find IBM mainframes in HPC, but that's because HPC is not as sensitive for latency and reliably than online transaction processing, and, with mainframes, you are paying for that, not for TFLOPS.
      • zifpanachr23 1y ago
        Yeah the architectures focus on different things. The huge caches on the z series chips are designed primarily around the kind of latency sensitive workloads more common in finance than the massive floating point throughput often needed for big scientific computing.
• numpad0 1y ago
  Everyone's predisposed that "mainframes are obsolete", but why not use a mainframe? I mean, no one except for banks can afford one, let alone make back on opex or capex, and so we all resort to MySQL on Linux, but isn't the cost the only problem with them?
  • bob1029 1y ago
    > no one except for banks can afford one Banks smaller than the big ~5 in the US cannot afford anything when it comes to IT infrastructure. I am not aware of a single state/regional bank that wants to have their IBM on premise anymore - at any cost. Most of these customers go through multiple layers of 3rd party indirection and pay one of ~3 gigantic banking service vendors for access to hosted core services on top of IBM. Despite the wildly ramping complexity of working with 3rd parties, banks still universally prefer this over the idea of rewriting the core software for commodity systems.
  • dardeaup 1y ago
    Not the only problem with them. Not as easy to find skilled staff to operate them. Also, you become completely dependent on IBM (not fully terrible -- it's a single throat to choke when things go wrong).
    • speed_spread 1y ago
      It's hard to choke someone's throat when they already hold you by the balls.
      • dardeaup 1y ago
        Haha.. That's somewhat true but I'm sure that the customer account folks at IBM would prefer not to be screamed at by irate customers.
  • zokier 1y ago
    Density is also bad. You spend 4 full racks and get 208 cores. Sure, they might be the fastest cores around, but that gets you only so far when even off-the-shelf Dell server has 2x128-192 cores in 1U server. Similarly 64 TB of RAM is a lot, but that same Dell can have 3 TB of RAM. If I'm reading the specs correctly (they are bit confusing), z17 has only 25G networking (48 ports); the Dell I'm checking can have 8x200G network ports and can also do 400G networking. So the single 1U commodity server has more network bandwidth than the entire 4 rack z system. Sure, there will be lot of overhead in having tens-hundreds of servers vs single system, but for lots of workloads it is manageable and certainly worth the tradeoff.
• pjmlp 1y ago
  Besides all answers given already, one of the reasons Unisys keeps selling Burroughs, aka ClearPath MCP, is its security model. ESPOL/NEWP is one of the very first systems programming languages, being safe by default, with unsafe code blocks. The whole OS was designed with security first in mind, think Rust in 1961, thus their customers are companies that take this very seriously, not only running COBOL. The motto is unsurpassed security. https://www.unisys.com/product-info-sheet/ecs/clearpath-master-control-program-mcp/ https://www.unisys.com/product-info-sheet/ecs/clearpath-mast...
  • anthk 1y ago
    Not just security, but CPU hotplugging and resuming as if nothing happened.
    • wmf 1y ago
      I'm not sure hotpugging is still there.
      • deleted 1y ago
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      • chiph 1y ago
        At least partially - the technical introduction for the Z17 says that several items can be concurrently maintained (IBM-speak for hot-swapped). So far as major items like the processing units - maybe (still reading). (3.4mb PDF) https://www.redbooks.ibm.com/redbooks/pdfs/sg248580.pdf https://www.redbooks.ibm.com/redbooks/pdfs/sg248580.pdf > Four Power Supply Units (PSUs) that provide power to the CPC drawer and are accessible from the rear. Loss of one PSU leaves enough power to satisfy the power requirements of the entire drawer. The PSUs can be concurrently maintained I would think their customers would demand zero downtime. And hey - if BeOS could power down CPUs almost 30 years ago I would expect a modern mainframe to be able to do it.
        • wmf 1y ago
          All servers have hot-swap power supplies. (I'm pretty sure BeOS never actually powered off CPUs; it just didn't schedule anything. Linux "hotplug" works the same way today.)
• ianbicking 1y ago
  All these legacy answers don't really make sense for this Z17... it's a new mainframe supporting up to 64T of memory and specialized cores for matrix math/AI applications. I have a hard time believing that legacy workloads are calling for this kind of hardware. It also has a ton of high availability features and modularity that _does_ fit with legacy workloads and mainframe expectations, so I'm a little unclear who wants to pay for both sets of features in the same package.
  • wmf 1y ago
    I've heard that the AI features are used by banks for fraud detection. I guess some banks are also growing their transaction volume. I agree that many mainframe workloads are probably not growing so what used to require a whole machine probably fits in a few cores today.
    • dardeaup 1y ago
      Thanks for mentioning. This makes sense.
  • deleted 1y ago
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  • rbanffy 1y ago
    You won't see mainframes doing AI training, but there is a lot of value in being able to do extremely low-latency inference (which is why they have their NPU on the same chip as the CPUs, just a few clock-cycles from the cores) during on-line transaction processing, and less timing-critical inference work on the dedicated cards (which are a few more nanoseconds away).
  • flomo 1y ago
    Additionally, IBM marketing likes the implication that mainframe CPUs are 'the best'. If you can buy a phone with an AI processor, it only makes sense that your mainframe must have one too. (And IBM will probably charge you to use it.)
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• bayindirh 1y ago
  If I were a bank, I'd order one of those and put all the financial modelling and prediction load on it. Like real time analysis to approve/deny loans, do projections for deciding what to do in slower moving financial products, predicting some future looking scenarios on wider markets, etc. etc. simultaneously. That thing is dreadnought matmul machine with some serious uptime, and can crunch numbers without slowing down or losing availability. or, possibly, you can implement a massively parallel version of WOPR/Joshua on it and let it rip scenarios for you. Just don't connect to live systems (not entirely joking, though). P.S.: I'd name that version of the Joshua as JS2/WARP.
• beAbU 1y ago
  Cloud is basically an infinitely scalable mainframe. You have dedicated compute optimised for specific workloads, and you string these together in a configuration that makes sense for your requirements. If you understand the benefits of cloud over generic x86 compute, then you understand mainframes. Cloud is mainframes gone full circle.
  • cameron_b 1y ago
    But latency The cache design in the Z is so different from cloud computing for collaborative job processes.
  • rbanffy 1y ago
    > Cloud is mainframes gone full circle. Except that now you need to develop the software that gives mainframes their famed reliability yourself. The applications are very different: software developed for cloud always needs to know that part of the system might become unavailable and work around that. A lot of the stack, from the cluster management ensuring a failed node gets replaced and the processes running on them are spun up on another node, all the way up to your code that retries failed operations, needs to be there if you aim for highly reliable apps. With mainframes, you just pretend the computer is perfect and never fails (some exaggeration here, but not much). Also, reliability is just one aspect - another impressive feature is their observability features. Mainframes used to be the cloud back then and you can trace resource usage with exquisite detail, because we used to bill clients by CPU cycle. Add to that the hardware reliability features built-in (for instance, IBM mainframes have memory in RAID-like arrays).
  • pjmlp 1y ago
    While I agree with the sentiment, for me it feels more like UNIX gone full circle. Instead of having everyone doing telnet, rsh and X Windows connections into the team's development server, we now use ssh and the browser alongside cloud IDEs.
• mhh__ 1y ago
  The funny thing is that if they spun out half of the mainframe thing into something they could compete with people might actually buy them. Most firms have so-so software, in need of ultra reliable hardware, not everyone is google
• musicale 1y ago
  People who want 64TB of memory in a single system.