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Fibre Channel research

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 requirements for accessing mainframe disk storage.
Enterprise disk storage has this annoying issue that the disk arrays are: HeavyPower-hungryRidiculously expensive An example: DS6800 is widely known to be an unreliable platform, and I would certainly never run a mainframe on it based on my experiences repairing mine. However it is as small as disk arrays get, but it is still 50 kg empty, and consumes 500W of power!
However the DS6800 is kind of a black sheep in reliability. What if we look at something bigger and better? The big brother DS8000 is known to be rock solid for example. The down…
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Mainframe setup 1.0

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 it seems like at least some folks enjoyed the stream.

Given that the stream content is somewhere around 12 hours, I figured a written walk-through of what we connected and why is in order. This is it.

The main connections you will need to your mainframe are:
Power Fibre Channel (FICON and/or FCP)Ethernet FiberEthernet Copper (Management) Power Power has already been covered in the Powering the mainframe article with the notable update that connecting both power cables for some reason trips the fuse in the datacenter. The manual says this:
Depending on the server configuration, this leakage cu…

Streaming setting up the mainframe

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 (@blueCmd) August 9, 2019 As I mentioned it will be recorded and I will post the uploaded videos here after the fact unless something catastrophic happens.

Update: The stream was successful! You can watch the recording here:

Powering a mainframe

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 datacenter staff, not needing a forklift in their day-to-day, had managed to solicit the services of a forklift, the associated operator, and some very handy folks to help navigate the mainframe from the storage space to its final location.



After some intense period of fighting the inclination of the road between the storage facility and the cage (and a door that was a bit too small) it was finally in place. Incidentally we were forced to trust the wheels on this pretty rough floor. I did not expect it to roll that well on raw concrete, I was pleasantly surprised. This thing is a tank!

Now, everybody wanted to see if it was working. My machine did not come with a power cable so I had to so…

Exploring and Repairing an DS6800

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 as it develops.



Note: The post has been moved to its own site to allow for other interested parties to contribute. Turns out there are quite a number of people that want to help :-).

Continue reading at https://ds6800.mainframe.dev.

FICON HBAs: The mysterious Bus-tech

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 to you. Most commonly you will use a protocol called FCP (protocol 0x08), which confusingly stands for Fibre Channel Protocol, which is the protocol responsible to moving SCSI commands over Fibre Channel. Another relatively new protocol is FC-NVMe (protocol 0x28) which is for, wll, NVMe over Fibre Channel without going through any SCSI layers. Another one is FICON which uses protocol 0x1B or 0x1C depending if the frame is from or to a control unit.

A host bus adapter (HBA) is a device that enables a computer to access a network, more or less always some sort of storage network and most commo…

Brocade Fabric OS downloads

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 taken down, but at least it helped somebody I hope.

These downloads worked for me and are hash-verified when I could find a hash to verify against. Use at your own risk etc.

The URLs are: ftp://ftp.hp.com/pub/softlib/software13/COL59674/co-168954-1/v7.3.2a.zip ftp://ftp.hp.com/pub/softlib/software13/COL59674/co-157071-1/v7.2.1g.zip ftp://ftp.hp.com/pub/softlib/software13/COL59674/co-150357-1/v7.1.2b.zip ftp://ftp.hp.com/pub/softlib/software12/COL38684/co-133135-1/v7.0.2e.zip ftp://ftp.hp.com/pub/softlib/software13/COL22074/co-155018-1/v6.4.3h.zip ftp://ftp.hp.com/pub/softlib/software11/…