A collection of articles about me building, fixing, hacking and modding stuff.
Given that the last post on this blog was a bit more than 2 years ago it should not come as a surprise to anyone; I feel like I have sufficiently scratched the mainframe itch and have moved on to other projects. I have spent the last few months getting all my mainframe equipment into the hands of the next-generation of hobbyists and since a week or so I am now officially sans mainframe. This also…
Yesterday after more than a year's delay my zBC12 mainframe finally booted up. This is a machine that was donated to me in hopes to advance the hobbyist community, which I am eternally grateful for. Image 1: Athena, the zBC12 that just now got online Then what is the main selling point of the zBC12 versus the z114? You might recall my article System z on contemporary zLinux where I explained that…
In this post I want to dig deeper into a phenomenon that I spent a few day debugging with friends. It will be a story of a behavior that seems illogical at first glance, broken even, but will seem feasible in the end. Let's begin! Things you will need: The scenario requires one host and one switch minimum*. In our example we will use two Linux hosts, an Arista DCS-7050S switch, and an Arista…
I have done systems administration for as long as I remember, and while I have set up countless of services and servers - I have quite limited experience working with the full life-cycle of truly enterprise software. Therefor, I thought it would be interesting to understand more on how one would plan for and execute updates on an IBM Z Series mainframe. If you consider a typical Linux system you…
I have to make a post mentioning the last couple of months, anything else would just be weird I feel. I hope you all are doing as well as can be in these unpredictable times. I know I have been personally affected by this pandemic in multiple ways yet I feel fortunate - things could have been so much worse. While I am one of the lucky people who work in a job that lends itself reasonably well to…
Wow, time flies. In the past months I've been working on a handful of projects related to the mainframe, but nothing that is really finished - so I thought I would summarize some work I've been doing instead. Things I've been up to since last post: Learning about PCIe and (not so successfully) adding it to Fejkon Repairing my DS6800 disk array Debugging why the circuit breaker disconnects when…
The latest project I've been working on is a custom card that will allow me to interface any mainframe using the FICON protocol. I have a lot of ideas on how this could help a lot of hobbyists out there, and possibly folks doing development for mainframes as well. For my own purposes, it would allow me to not be reliant on my (still broken) DS6800 array. DE5-Net card running fejkon "But why would…
The last couple of weeks I've been traveling for work, and I spent a long flight reading some publications I had saved up about mainframe and Fibre Channel. I will talk about some good sources of information later, but for now know that FICON runs over Fibre Channel, and indeed a lot of the reasons behind why Fibre Channel is known to be really reliable is that it more or less came out of IBMs…
A couple of weeks ago we streamed installing the mainframe in the datacenter from scratch. When we arrived the only thing that was there was the mainframe itself, some power cables, a fiber drop for Internet, and some shelves. Nothing was connected together. Being a datacenter it is of course noisy from all the fans, so I am not surprised that streaming with sound did not work out. Never-the-less…
I want to try something I have never done before. I will stream setting up the mainframe. Ok, let's try this. Stream for setting up the mainframe is going to be at twitch.tv/mainframedev . I aim to start tomorrow (Sat) at 13:00 CEST / 11:00 Z. It's going to be recorded as well. Tune in and chat with me and my friend soundgoof when we install a mainframe from scratch. — Christian Svensson…
The last few days have been eventful. I was contacted by the datacenter that the mainframe's cage is now ready for moving in, and the power has been made available. Very exciting! I grabbed my home-made power cables (more on that later) and my best screwdrivers and set off to the datacenter. The view next to the datacenter The datacenter staff, not needing a forklift in their day-to-day, had…
This is an knowledge base of various information about the IBM DS6800 that I hope will be useful if you ever need to repair one of these disk arrays. The intention is for this post to be updated as new information becomes apparent or outdated. Right now the post is very much in a pre-alpha state and I hope to have more of a narrative down the road, but I thought it would be fun to share the story…
Commonly when talking about Fibre Channel the assumption is that you are talking about attaching some sort of storage device to some resource that wants to use that storage. However, Fibre Channel itself does not care about the storage part. Fibre Channel only facilitates opening a channel between two devices, which is referred to as nodes in Fibre Channel lingo - then what you do after that is up…
Fabric OS is what runs on the SAN switches I will be using for the mainframe. It has a bit of annoying upgrade path as the guldmyr blog can attest to. TL;DR is that you need to do minor upgrades (6.3 -> 6.4 -> 7.0 -> ... > 7.4) which requires you to get all Fabric OS images for those versions. Not always easy. So, let's make it a bit easier. Hopefully this will not end up with the links being…
I am back in Switzerland. It has been a good two months away from work, and the first morning after coming back I rushed to the office to unpack and inspect the goods that will hopefully make the mainframe come alive. So far the equipment is: DLm2000 virtual tape system 1x Virtual Tape Engine (VTE) 1x Access Control Point (ACP) 2x Brocade 5100 SAN switch 1x Arista DCS 7050S-64-R 10/40 Gbps switch…
This is going to be a short update to share some good developments in the project. First of all: the mainframe has cleared customs and has been received by the datacenter. Customs caused a bit of a headache as eBay lists the sale price as the "Buy it now" price even if an agreement was put in place. This is usually fine as they values do not diverge a lot but in this case it was $300,000 vs…
My earlier blog article named Buying an IBM mainframe did get way more exposure than I could have hoped for, thanks to everyone that read it! The discussions on various forums did naturally evoke some interesting questions. Mostly they are "Why?" in various shapes or forms. It is a totally understandable reaction, and thus I want to present some of the things that I am excited about having…
IBM System z supports a handful of operating systems; z/VM, z/VSE, z/OS, z/TPF, and finally zLinux. All the earlier mentioned OSes are proprietary except for zLinux which is simply Linux with a fancy z in the name. zLinux is the term used to describe a Linux distribution compiled for S390 (31 bit) or S390X (64 bit). As we are talking about modern mainframes I will not be discussing S390, only…
I bought an IBM mainframe for personal use. I am doing this for learning and figuring out how it works. If you are curious about what goes into this process, I hope this post will interest you. I am not the first one by far to do something like this. There are some people on the internet that I know have their own personal mainframes, and I have drawn inspiration from each and every one of them.…
I've been learning about z/OS and MVS over the last couple of weeks using the Master the Mainframe course and also the highly affordable courses from Interskill. I wanted to build something proper so I built a thing that can backup a full z/OS system to CCKD files (same as what Hercules/Hyperion uses). With the fixes for 64-bit CCKD to Hyperion now merged, and the 64-bit cckddump tooling appears…
Introduction The Leopard is an OpenRack v1 compliant 12V server commissioned by Facebook to offer compute power. It consists of 2x Intel Xeon E5-2678 v3 and is available with either DDR3 or DDR4 memory. The model is manufactured by two vendors primarily: Quanta and Wiwynn. Leopard features a 24x PCIe slot which can fit either a PCIe card with low profile, or a riser card with 1x 16x and 1x 8x…
Let's say that you are a system administrator in a decently sized company. You're responsible for selecting new servers for a pretty decently sized upgrade round in your data centers, or maybe you're building a new datacenter. It's not that long ago this happened last time for your company, but since we're living in an ever-changing world things of course are complicated. What do you do? Let's…
Christmas is the time I get some time away from work to tinker on those projects I've put off for so long. One of them has been to build something cool with the hardware I have acquired over the years. Let's have a look on what the current state of my laboratory looks like! The Hardware I and a couple of friends rent rack space in a datacenter in Stockholm, Sweden. We have about 4U rack space each…
A lot of people probably have that hard bug they spent a lot of hours trying to solve. Almost 1.5 years after solving my hardest bug I got nostalgic and thought "Hey, this was pretty cool! I should write about it to not forget it". Since it's so long ago there might be things I misremember, but the gist of it should still apply. Let's jump to it! Presenting: "The curious case of the crashing…
I moved all old posts to blogger.com just now. Most, but not all, of the articles seems to have kept their layout somewhat intact - ping me if something looks very broken and I'll fix it right away! I have updated the front page articles, but the older ones are still missing pictures and images.