Why Do Mainframes Still Exist? What's Inside One? 40TB, 200+ Cores, AI, and more!

Comments · 2.6K

• ST

  @stevekristoff4365 · 2 years ago · pinned

  DDR4 RDIMM memory is 3200 MT/s at 64bit (or up to 72bit w/ ECC) which 8bits/byte would give you 25.6GB/s. &nbsp;what you are missing is that memory is multi-channel. &nbsp;Intel Xeons can go up to 8-way memory, AMD Epyc can go up to 12 way. &nbsp;So you&apos;re talking 204GB/s or 307GB/s. &nbsp; DDR5 RDIMMS are even faster so throughput would be greater. &nbsp; What I do not know is the inherit latency of memory access (core to core, or package to package) where I suspect the mainframe would be better (lower latency). &nbsp; Is main memory on the z16 static ram or dynamic? &nbsp;<br><br>Likewise PCIe I/O is up there on server platforms, a dual processor AMD Epyc has 128 PCIe lanes (Gen 4 for Milan, or Gen 5 for Genoa) for a total of 256 PCIe lanes of generation type.<br><br>However should be stated that just pure lane counts does not compare well. &nbsp; Mainframes are set up to OFFLOAD a lot of signal &amp; I/O processing much more than mid-range/server. &nbsp;(concept in the server world is just taking hold with dedicated processing units (APU/DPU) but mainframes have been doing that forever. &nbsp;<br><br>There are a bunch of other items as well, but it&apos;s like comparing an armored personnel carrier to a car. &nbsp;Both can get you from A to B but one is much more robust. &nbsp;:)

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• DR

  @dragunzonline · 2 years ago

  I work on IBM Z and POWER as a chip designer. Awesome to see our work presented.

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• FR

  @frankbosco293 · 2 years ago

  I retired in 2020 and I refused to work on z16 because it would have kept me working to age 81! But I was a z system architect up thru z15 and had worked on the mainframe since the system 360 model 85 which contained the very first memory cache. I always knew I was on a team working on one of the most truly great products ever conceived. I loved this presentation. Thank you.

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• AL

  @alexhiatt3374 · 2 years ago

  This is INSANE, every time you mentioned a feature I thought there was no way they could top it. And then they&apos;re just casually like &quot;oh yeah and these 64 5.2GHz cores can also run 2 bajillion VMs and encrypt all of main memory and correct for cosmic rays&quot;

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• MA

  @marktwain5232 · 2 years ago

  Thank you so much, Dave, for this fascinating tour! Now retired, I worked 41 years as an Application Development Software Engineer in the barbarian Microcomputer Revolution of the great unwashed out on the vast steppes. I always wondered what was still going on high up on Mount Olympus in the original Birthing Power Mainframe World! Now I have gotten a glimpse of the still evolving Sacred Temple! I absolutely LOVED this! Kudos to all of you Mainframe Engineers and Technicians commenting on this thread who worked in this World in the lofty Clouds! Homage to all of you!

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• MI

  @mikeklaene4359 · 2 years ago

  In 1969 I landed a programmer trainee job at a department store in Cincinnati.<br>We had a 32K 360/30 running 360 DOS and &nbsp;Assembler was the first programming language I learned.<br>After being away from mainframes for 20 years, I applied for a position at a shop that had 6 System 390&apos;s. &nbsp;The hiring manage asked if I thought that I could still do assembler - I said if &quot;D2&quot; was still the op code for the MVC instruction - then yes. &nbsp;He was surprised that I knew most of the op codes and could even read a core dump.

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• T3

  @T3CKsnipes · 2 years ago

  Dave, was a pleasure helping give you a tour of the Z manufacturing floor! Absolutely love this video!

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• TO

  @TomCee53 · 2 years ago

  The first machine that I was responsible for as a system programmer was an IBM 4341 back in the early 1980s. It was used for software development and testing running VM/CMS and supported 6 concurrent users. They’ve come a long way.

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• TH

  @thecodemachine · 2 years ago

  I am proud to have worked on the I/O subsystem code. I even updated the boot loader which was originally written before I was born.

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• DA

  @davidioanhedges · 2 years ago

  The basic premise is it is absurdly fast, will take the required system load and throughput, and is never ever turned off or rebooted, and never fails for any reason whatsoever...

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• CC

  @CCP187 · 2 years ago

  I remember my first IT job in 1999 working with NT40 and wondering what was up with the ancient mainframe guys at my company. &nbsp; Now I&apos;m the old man. &nbsp; Respect.

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• TA

  @tanjbennett4572 · 2 years ago

  You overlooked a key reliability feature .. the IBM Z series includes extensive internal self consistency checking of the logic inside the CPU so it can detect when the logic fails and retry a transaction, shutting down the core if necessar. &nbsp;&quot;Commodity&quot; CPUs are tested after manufacture but after passing test most later errors are silent. &nbsp;Recent testing for silent errors in servers at Google and AWS have found that silent errors are quite significant. &nbsp;IBM has taken them seriously for decades.

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