Skip to main content

firesteel rods

Firesteel is a great metaphor for for system clustering, HA and DR. Firesteel or "ferrocerium rod" is a metal rod with properties similar to flint and steel. The purpose is to make fire. These rods are used in two parts. The rod and the striker. The striker is very simple and can be similar to a tab of a poptop can or the spine of any knife (blade too but that's not a great idea even though the rod is a softer metal)

The metaphor...

Firesteel comes in a number of lengths and sizes. So the question is which size is the right size?

First of all the firesteel should be just one of the three combustion options you have in a true DR situation. A normal lighter, firesteel and magnifying lens are ideal. You should also know how to build a bow drill and a compression stick.

But choosing the right length, width, use-count, and packaging are all very important.

  • the longer and wider the rod the more it costs. You can pay $30 for a bare 6in long 1/2in wide rod.
  • some smaller rods are connected on some cordage to keep the striker close to the rod.
  • some rods have plastic holders for ease of use and will also have a whistle
  • some are just meant to be worn around your neck or attached to you sheath.
  • not all rods are the same. They vary in the number of strikes (regardless if there are sparks) 12,000, 10,000, 3000, 1500. I have noticed that the 1500 generates bigger sparks and the rod is softer so I must be shaving off more material per strike,
And while all of this is reasonable there is one big weakness of the rods. Saltwater. I'm told that saltwater is a firesteel's mortal enemy. If the rod is submerged in saltwater it will not strike or I assume degraded.

So as a metaphor for system DR and HA this is it.

Have a few extra rods with you. Put some in ziplocks in your pack, hang on your knife or belt and accessible on your pack. Assume you're going to lose them and have a backup like a lighter or bowdrill.

Have a few extra machines in your network. plan to share the workload, keep some hardware in reserve, do not put all your money into just a few machines.

STORY:  I have a cluster of CoreOS machines in my PAN (private area network). I use them to develop my CoreOS and container ideas as well as staging work product for production. Something went very wrong last night when my wireless and wired networks became partitioned. I'm still not sure what happened but it's easy to recognize that my [a] and [b] plans failed. If the system had not corrected itself this morning I would have been moving to [c] which would allow me to get back to work but I would have lost a few days of R&D. I once had an idea that I should "commit everything". I think that plan is coming back so that plan [c] becomes plan [d] and the new [c] move the work to a different site.

This system failure and my DR/HA plan is a perfect metaphor.

Popular posts from this blog

Prometheus vs Bosun

In conclusion... while Bosun(B) is still not the ideal monitoring system neither is Prometheus(P).


I am running Bosun in a Docker container hosted on CoreOS. Fleet service/unit files keep it running. However in once case I have experienced at least one severe crash as a result of a disk full condition. That it is implemented as part golang, java and python is an annoyance. The MIT license is about the only good thing.

I am trying to integrate Prometheus into my pipeline but losing steam fast. The Prometheus design seems to desire that you integrate your own cache inside your application and then allow the server to scrape the data, however, if the interval between scrapes is shorter than the longest transient session of your application then you need a gateway. A place to shuttle your data that will be a little more persistent.

(1) storing the data in my application might get me started more quickly
(2) getting the server to pull the data might be more secure
(3) using a push g…

Entry level cost for CoreOS+Tectonic

CoreOS and Tectonic start their pricing at 10 servers. Managed CoreOS starts at $1000 per month for those first 10 servers and Tectonic is $5000 for the same 10 servers. Annualized that is $85K or at least one employee depending on your market. As a single employee company I'd rather hire the employee. Specially since I only have 3 servers.

The pricing is biased toward the largest servers with the largest capacities; my dual core 32GB i5 IntelNuc can never be mistaken for a 96-CPU dual or quad core DELL

If CoreOS does not figure out a different barrier of entry they are going to follow the Borland path to obscurity.

Weave vs Flannel

While Weave and Flannel have some features in common weave includes DNS for service discovery and a wrapper process for capturing that info. In order to get some parity you'd need to add a DNS service like SkyDNS and then write your own script to weave the two together.
In Weave your fleet file might have some of this:
[Service] . . . ExecStartPre=/opt/bin/weave run --net=host --name bob ncx/bob ExecStart=/usr/bin/docker attach bob
In sky + flannel it might look like:
[Service] . . . ExecStartPre=docker run -d --net=host --name bob ncx/bob ExecStartPre=etcdctl set /skydns/local/ncx/bob '{"host":"`docker inspect --format '{{ .NetworkSettings.IPAddress }}' bob`","port":8080}' ExecStart=/usr/bin/docker attach bob
I'd like it to look like this:
[Service] . . . ExecStartPre=skyrun --net=host --name bob ncx/bob ExecStart=/usr/bin/docker attach bob
That's the intent anyway. I'm not sure the exact commands will work and that's partly why we…