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Inside the new IBM LinuxONE Rockhopper 4 rack-mount


There are 18 species of penguins. The largest is the Emperor penguin, and one of the smallest is the Rockhopper. When the IBM LinuxONE was released and these names graced the large and small sizes, I thought it was fun and brilliant. I'm happy to report that with the fourth iteration of the LinuxONE, these names are brought back, and have been taken to a whole new extreme, the smallest IBM LinuxONE Rockhopper 4 is not only fits in a 19” rack spot, it fits into a 19” rack. That's right! The smallest Rockhopper is a rack-mount server! And that's what I want to share more details about.

First off, just have a look! When I joined IBM in 2019 and stepped inside one of the z14 frames in Poughkeepsie, I didn't think I'd be talking about rack-mount systems today.

If you're looking for deep technical information this new system, the name you want to look for in the technical documents is the AGZ, and there's a lot of excellent information in the IBM z16 A02 and IBM z16 AGZ Technical Guide, which I'm drawing from in this blog post. And in case you're wondering about the A02, that's the larger, single frame sibling of the AGZ, which was also announced this month.

As for configurations, I mentioned the 10U system as being the smallest configuration. In this configuration, you can expect the following components:

  • 1 CPC drawer, packed with 4.6GHz IBM Telum processors
  • Ethernet switches
  • Hardware Management Consoles (HMCs) with Service Element (SE) Servers (active amd backup)

Snagged directly from the Technical Guide, the 10U configuration is shown in the chart below, alongside various other configurations are available with up to 3 PCIe+ I/O drawers.

Need more CPC drawers? We've got you covered! These rack-mount systems can have up to two CPC drawers, alongside a varying number of PCIe+ I/O drawers.

Need even more? Well, that's all that will fit in your rack! At this point, you really want to start looking at one of the LinuxONEs released back in September.

These systems are installed by an IBM service support representative (SSR) in an ASHRAE class A3 data center environment. The rack itself and Power Distribution Units (PDUs) supplied by the client, all of which is confirmed ahead of time to match the specifications required, based on the IBM z16 and LinuxONE Rockhopper 4 Rack Mount Bundle Installation Manual for Physical Planning (IMPP). Special rails are shipped with the system, and that's where I found this gem in the Technical Guide, an example of a shipping crate!

Now, if you've been following the news about this launch, you've probably seen the above glamour shots of the new systems. Thankfully, I get to work with PJ Catalano, and he was able to take some photos from the test floor where they actually have a bunch of them! Want to see a rack-mount actually installed somewhere? And some of the internal bits? You're in the right place.

Since I just mentioned the shipping pod, PJ surprised me this past weekend by snapping a photo of one they had all packed up! How cool!

Side note, if you're interested in learning more about the fascinating story of how mainframes are packaged for shipping, and shipped, this Terminal Talk episode from 2018 is a delight: Episode 33 - Sharon Spaulding - Mainframe Packaging.

But now we can get into the other fun stuff, an installed system in its fully glory!

Now for the big surprise, it's more than just the greatness of the LinuxONE we know and loved packed into a smaller package! In addition to all the engineering effort you might expect to put components we're familiar with, from RAIM to the new IBM Telum processor I talked about in my blog post, A tour inside the IBM z16, this rack-mount system does have a few other changes worth noting.

For one, fan covers are new for rack-mount. For the traditional servers that come in the frames, you have those beautiful and very functional doors, which have an air filter in them. Since there's no guarantee there is a door on the rack mount system there is a Field Replaceable Unit (FRU) fan covers with filters.


It probably goes without saying that it's also air-cooled, which means that lovely Telum processor has a giant heatsink!

Want to learn more? I talked about LinuxONE in this article because that's been my focus, but you can follow the guidance for specifications outlined in the IBM z16 AGZ documentation, so the IBM z16 A02 and IBM z16 AGZ Technical Guide mentioned above really is a gold mine. The key difference worth noting between these machines is the type of processor, with the LinuxONE including the Integrated Facility for Linux (IFL) processors (still Telum!) instead of the general-purpose processors (CPs), or a mix of IFLs and CPs that you may find in a z16. You'll be able to browse a lot more technical specifications as well as see more configuration charts. I had a lot of fun digging into it, and I think you will too!


Tue April 18, 2023 02:42 PM

@Ricardo Bánffy the IBM z16 AGZ runs Linux both on the low-level hypervisor (PR/SM) in logical partitions (LPAR) and alternatively as guests of z/VM (where z/VM would be running in the LPAR).

A third way to run Linux on Z is KVM guests. You can run Linux on LPAR and then virtualize guests there.

And then there's zCX, which allows one to run Linux containers inside z/OS.

Mon April 17, 2023 04:40 PM

Does it run z/VM to host Linux VMs or does it host the VM on the low-level hypervisor?