Oh how I love the Good Regulator Theorem

Every now and then I like finding links between Cybernetics (or Systems Dynamics, or Systems Thinking, pick your favorite variation) and System Administration. I am not the only one in this. For example Matt Simmons has written about how System Administrators act as homeostasis mechanisms for the systems they manage. And minutes before this slide came up my way:

Rule #4: Monitoring systems need to be more available and scalable than the systems being monitored

which reminded me of a theorem and a law as applied in the monitoring systems domain. The Good Regulator Theorem states that every good regulator of a system must be a model of that system. You provide the monitoring system with a model of what you need to monitor in its appropriate DSL or clickware. The more precise the model, the better the monitor.

The rule in the slide ties closely with the law of requisite variety where the variety in the control system must be equal to or larger than the variety of the perturbations in order to achieve control. Think about it: At least the downtime of your monitoring system needs to be significantly less than that of the system monitored. Otherwise what exactly are you seeing? Think of Nyqvist-Shannon sampling here. Or as John Gall has put it in The Systems Bible, a system is no better than its sensory organs.

Is it practical to make these observations? For everyday job not really, but when I find such connections between “obscure” theory (obscure for admins) and system administration, I always smile :)

PS: @adrianco during the discussion left another piece of advice:

on a later slide I said best to use two independent monitoring systems then they can watch each other.

Flash Boys

“All of a sudden the market is all about algos and routers. It’s hard to figure this stuff out. There’s no book you can read.”

I first heard about high frequency trading more than 10 years ago from a bright person who occupied the desk next to mine at the lab. I thought it was interesting but I could not foresee what it would come to mean today.

Flash Boys is a book by Michael Lewis that deals with the implications of HFT and dark pools to the stock market. It chronicles the journey of Brad Katsuyama from when he first notices that the market view on his computer screen is an illusion, his effort to understand the mechanisms that rule the market, building a team for the task and ultimately quitting his well paid job in order to create a fair marketplace for the investors. That marketplace is the IEX. I would call the IEX a white pool though.

I like the book for a number reasons: First it is about a good regulator (the cybernetic term). Katsuyama wants to understand something so complicated and complex that no one else really understands. He needs to create a market view that is explainable to investors to the microsecond and according to the book this is done.

The story behind team formation is interesting too. Every member in the team has something in their life worth reading about and they offer value to the team formed. I found lessons in team formation there.

There exists this interesting term called the Regulatorium: a complex system of rules and requirements where each rule is necessary because of another, related rule. This leads to collusion between regulators and those regulated preventing change. And the Flash Boys wanted to change the system.

The moral values of Katsuyama appeal to me. A potential investor asked: “Why does a person take the harder path? It’s a different situation from what you typically see. If it works, he will make money. But he’ll make less” than if he had stayed at RBC.

The technical problems they faced I understood and I loved some of the solutions (“coil the fiber”). I could actually follow this fast paced, well-written chronicle with just a bit of googling for a few financial terms (and I have never dealt with a stock market).

I finished the book with a “damn, I want to work with these guys!”. So Brad, if you ever read this and in need of a remote worker in a different timezone, ping me :)

Chromecast

I bought myself a present yesterday: A Chromecast. Why you may ask? Mostly because I wanted something to send Youtube videos to the TV for the kids. I was doing it with OpenELEC on the Raspberry Pi, but it was not the most straight forward thing for the children.

Setting up the device was not straight forward, but this was not Chromecast’s fault. I had to fiddle with the WiFi channel of my home router (I switched from auto selection to some specific channel) in order to make it see the home network. After that, the device connected to the Net, upgraded itself and worked like a charm.

Things I tested:

  • Driving the Chromecast from an iPad and a Nexus 7. Youtube videos displayed fine and you could use the tablet for other stuff after it started streaming the video.
  • Tab casting from a Windows machine using Chrome.
  • Full screen casting of a windows machine, again using the Chrome extension.

Tab and full screen casting has about a 1.5 second delay between the laptop and the TV screen, but once you get used to it, it does not really bother you.

After one day of using it I believe that Chromecast is great both the idea and its execution. But I find it overkill for Greece where you’d mostly stream Youtube and use no other applications. Granted it is cheaper than something like Airtame, but there may be cheaper options. What sold me, was its ability to work with Chrome in order to share your desktop to the screen. Sort of a Hangout screen sharing with your TV.

Now let’s see whether edX streams through Chromecast just like Coursera does.

Flame speed

As I was watching people passing to one another the Easter flame, I could not help but wonder:

We know that the wave’s speed is about 12m/s. So what is the speed of passing the flame?

Network scientists would also be interested in other stuff, like who passes the flame to who, or to how many and the like.

Happy Easter everyone!

Weber–Fechner Law

Αυτό θα είναι ένα ακόμα μη ολοκληρωμένο ποστ. Έχει πέσει πολλή δουλειά και τα καλά τα ποστ θέλουν φροντίδα και καιρό τώρα δεν το κάνω αυτό. Αλλά είναι καλύτερα να ρίξεις κάτι μισό στον αέρα, παρά να το ξεχάσεις στο ντουλάπι. Κάποιος μπορεί και να ενοχληθεί και να σε αναγκάσει να γράψεις παραπάνω.

Βλέποντας λοιπόν το τέλος της ομιλίας του Δημήτρη Αχλιόπτα που έκανε ένα γύρο στο web, χάρη στο διάγραμμα του θυμήθηκα τον Weber-Fechner Law. Να δεις που τον είχα ξανακούσει, α εδώ.

Διάβασα αρκετά σχόλια για αυτά που λέει. Τα περισσότερα ήταν out of context κατά την γνώμη μου. Ένας από τους λόγους είναι πως πλασαρίστηκε ως ομιλία, ενώ είναι φανερό πως είναι τα τελευταία 15 λεπτά ενός μαθήματος και πως ο Αχλιόπτας τα έχει “πάρει”. Οι όποιες διαφωνίες μου με αυτά που λέει είναι μικρές (π.χ. δεν κάνουν όλοι εφτάωρες συνεντεύξεις και δεν κάνουν πάντα). Θα σταθώ όμως στο γράφημα που παρουσίασε. Διάβασα πως πολλοί λένε πως δεν είναι επιστήμη αυτό που έκανε και πως βγήκε και από τα χωράφια του. Και λοιπόν; Χρησιμοποίησε μια γραφική παράσταση για να δείξει αυτό που πιστεύει. Ναι είπε απόδειξη, αλλά συγνώμη δεν εξηγούσε αν το P=NP κιόλας. Αλλά στο κάτω-κάτω δεν απέχει αυτό που είπε από το γράφημα του Weber-Fechner Law (που είναι επίσης εμπειρικές παρατηρήσεις).

Fechner's Law
Fechner’s Law

Σήμα είναι ο πόνος, σήμα και η ευτυχία.

[image source]

How legacy systems die

The news server that a friend was maintaining had stopped responding for a while. Leafnode complained with:

warning: HOSTNAME: cannot resolve host name: Name or service not known

So I emailed my friend and asked. It seems that the hardware of HOSTNAME had failed, and that after a month or so I was the only person who wondered about its fate. No plans to put it back online exist.

And with that I realized that the USENET is now dead for me.

Παράσιτα

Μια και ο Θεοδωράκης και ο Βαρουφάκης πιστεύουν πως το πρόβλημα της Χώρας είναι τα παράσιτα, θυμήθηκα την αρχή από ένα κείμενο του Schneier:

“My big idea is a big question. Every cooperative system contains parasites. How do we ensure that society’s parasites don’t destroy society’s systems?

It’s all about trust, really. Not the intimate trust we have in our close friends and relatives, but the more impersonal trust we have in the various people and systems we interact with in society. I trust airline pilots, hotel clerks, ATMs, restaurant kitchens, and the company that built the computer I’m writing this short essay on. I trust that they have acted and will act in the ways I expect them to. This type of trust is more a matter of consistency or predictability than of intimacy.”

Παραδόξως με τους ορισμούς του Βαρουφάκη για τους παρασιτισμούς συμφωνώ. Από τότε που τυχαία στο Google Books έπεσα πάνω στον ορισμό του transactional leadership.

“Γεννήθηκε έξω από το παλιό σύστημα εξουσίας και προσπαθεί να δομήσει μια νέα πρόταση, για μια νέα χώρα.”

Και όσο μεγαλώνει θα αλλάζει. Αναγκαστικά. Και αναπόφευκτα ο Iron Law of Bureaucracy θα το κάνει μία από τα ίδια. Ή θα πρέπει να αυτοδιαλυθεί για να γλιτώσει.

[ * Random mode on; είναι αργά και δεν μπορώ να κοιμηθώ ]

When you have an idea you won’t work on, share it

Someone else will pick it up and do better work than you ever planned to.

The story goes like this: I was always fascinated by surveys like the ones Netcraft did. Over the years, more organizations added their own surveys, redoing what Netcraft did, or complementing what already existed with new research and data. I was always interested in redoing some of this stuff at the national scale, namely observing how the global surveys compare with similar ones about “greek” IP addresses or .GR domains.

Alas, two were the problems. .GR data is not easy to get access to and of course time there is not.

However a few months ago I bumped into this DNS census list which contains .GR data one can work on. And stuff that I wanted to do came back to haunt me. Knowing that I would not be able to find the time to do so, I hinted to my friends at Project Zero what would be something nice to work on. A few weeks later they came back with their preliminary results.

I am eagerly waiting for the next parts of their analysis.