In the previous fault detection article, we saw how we can cover a lot of ground in fault detection with simple methods and technology that is available today. It had an example of a simple but effective approach to find sudden spikes (peaks and drops) within fluctuating time series. This post explains the continuation of that work and provides you the means to implement this yourself with minimal effort. I’m sharing with you:

• Bosun macros which detect our most common not-trivially-detectable symptoms of problems
• Bosun notification template which provides a decent amount of information
• Grafana and Graph-Explorer dashboards and integration for further troubleshooting

As we try to retain visibility into our increasingly complicated applications and infrastructure, we’re building out more advanced monitoring systems. Specifically, a lot of work is being done on alerting via fault and anomaly detection. This post covers some common notions around these new approaches, debunks some of the myths that ask for over-complicated solutions, and provides some practical pointers that any programmer or sysadmin can implement that don’t require becoming a data scientist.

Updated oct 1, 2014 with a new Disk space efficiency section which fixes some mistakes and adds more clarity.

The Graphite + InfluxDB series continues.

• In part 1, “On Graphite, Whisper and InfluxDB” I described the problems of Graphite’s whisper and ceres, why I disagree with common graphite clustering advice as being the right path forward, what a great timeseries storage system would mean to me, why InfluxDB - despite being the youngest project - is my main interest right now, and introduced my approach for combining both and leveraging their respective strengths: InfluxDB as an ingestion and storage backend (and at some point, realtime processing and pub-sub) and graphite for its renown data processing-on-retrieval functionality. Furthermore, I introduced some tooling: carbon-relay-ng to easily route streams of carbon data (metrics datapoints) to storage backends, allowing me to send production data to Carbon+whisper as well as InfluxDB in parallel, graphite-api, the simpler Graphite API server, with graphite-influxdb to fetch data from InfluxDB.
• Not Graphite related, but I wrote influx-cli which I introduced here. It allows to easily interface with InfluxDB and measure the duration of operations, which will become useful for this article.
• In the Graphite & Influxdb intermezzo I shared a script to import whisper data into InfluxDB and noted some write performance issues I was seeing, but the better part of the article described the various improvements done to carbon-relay-ng, which is becoming an increasingly versatile and useful tool.
• In part 2, which you are reading now, I’m going to describe recent progress, share more info about my setup, testing results, state of affairs, and ideas for future work

Time for another side project: influx-cli, a commandline interface to influxdb.
Nothing groundbreaking, and it behaves pretty much as you would expect if you've ever used the mysql, pgsql, vsql, etc tools before.
But I did want to highlight a few interesting features.

A post about the magnificent darktable photo manager/editor and why I’m abandoning pixie

It's a pretty common thing in backend go programs to have multiple coroutines concurrently needing to modify a shared resource, and needing a response that tells them whether the operation succeeded and/or other auxiliary information. Something centralized manages the shared state, the changes to it and the responses.

Earlier this month we had another iteration of the Monitorama conference, this time in Portland, Oregon.

(photo by obfuscurity)

Graphite, and the storage Achilles heel

Graphite is a neat timeseries metrics storage system that comes with a powerful querying api, mainly due to the whole bunch of available processing functions.
For medium to large setups, the storage aspect quickly becomes a pain point. Whisper, the default graphite storage format, is a simple storage format, using one file per metric (timeseries).

Metrics 2.0 started as a half-formal proposal and an implementation via graph-explorer, but is broad enough in scope that it deserves its own website, its own spec, its own community. That’s why I launched metrics20.org and a discussion group.

This week I had the opportunity to present metrics 2.0 and Graph-Explorer at the Full-stack engineering meetup.

So you have a few devices with pictures, and maybe some additional pictures your friends sent you. You have a lot of pictures of the same thing and probably too high of a resolution. Some may require some editing. How do you easily create photo albums out of this mess? And how do you do it in a way that keeps a simple and elegant, yet flexible file/directory layout for portability and simplicity?

We (the Vimeo Staff) just released the 2013 Vimeo Holiday Special, embedded below.
(and I have a line in it! “Who’s behind this?”)

• Graphite’s metrics are strings comprised of dot-separated nodes which, due to their ordering, can be represented as a tree. Many other places use a similar format (stats in /proc etc).
• OpenTSDB’s metrics are shorter, because they move some of the dimensions (server, etc) into key-value tags.

I've been a graphite contributor for a while (and still am). It's a great tool for timeseries metrics. Two weeks ago I started working on Graphite-ng: it's somewhere between an early clone/rewrite, a redesign, and an experiment playground, written in Golang. The focus of my work so far is the API web server, which is a functioning prototype, it answers requests like

/render/?target=sum(scale(stats.web2,5.12),derivative(stats.web2))

I.e. it lets you retrieve your timeseries, processed by function pipelines which are setup on the fly based on a spec in your http/rest arguments. Currently it only fetches metrics from text files but I'm working on decent metrics storage as well.

This blog just got added to planet devops and infra-talk, so for my new readers: you might know me as Dieterbe on irc, github or twitter. Since my move from Belgium to NYC (to do backend stuff at Vimeo) I’ve started writing more about devops-y topics (whereas I used to write more about general hacking and arch linux release engineering and (automated) installations). I’ll mention some earlier posts you might be interested in:

Profiling a process run

black-box behavior testing processes/daemons

The above sounds like a marketing phrase and I’m just as skeptical of them as you, but I feel it’s in place. Not because GE is necessarily better, but it’s certainly different.

Client-side rendering of charts as opposed to using graphite’s server side generated png’s allows various interactivity features, such as:

Introduction

Graphite can show events such as code deploys and puppet changes as vertical markers on your graph. With the advent of new graphite dashboards and interfaces where we can have popups and annotations to show metadata for each event (by means of client-side rendering), it’s time we have a database to track all events along with categorisation and text descriptions (which can include rich text and hyperlinks). Graphite is meant for time series (metrics over time), Anthracite aims to be the companion for annotated events.
More precisely, Anthracite aims to be a database of “relevant events” (see further down), for the purpose of enriching monitoring dashboards, as well as allowing visual and numerical analysis of events that have a business impact (for the latter, see “Thoughts on incident nomenclature, severity levels and incident analysis” below)
It has a TCP receiver, a database (sqlite3), a http interface to deliver event data in many formats and a simple web frontend for humans.

I submitted a pull request to statsd which adds histogram support.
(refresher: a histogram is [a visualization of] a frequency distribution of data, paraphrasing your data by keeping frequencies for entire classes (ranges of data). histograms - Wikipedia)
It’s commonly documented how to plot single histograms, that is a 2D diagram consisting of rectangles whose

• area is proportional to the frequency of a variable
• whose width is equal to the class interval

Plotting histograms.. over time

Learned about Dell Crowbar the other day. It seems to be (becoming) a tool I’ve wanted for quite a while, because it takes automating physical infrastructure to a new level, and is also convenient on virtual.

I’ve been meaning to write about a lot of stuff in separate posts, but they kept getting delayed, so I’ll just briefly share everything in one post.

Similarly to how back in 2009 there was no browser that works in a way I find sane, and I started solving that with uzbl, now I'm fed up with the lack of an email client that works in a way I find sane. Uzbl turned out to be a bit cumbersome for my taste, so I switched to the uzbl-inspired but more pragmatic luakit browser, which is much in the same vein, except that all configuration, extensions, event handling, programmatic input etc are done by interfacing with lua API's. Now I want to build the "luakit of email clients". Let me explain what's that all about...

For the last few months, I’ve started to actively use hitchhiking as a means to travel between home and work. What started as a “I’m not sure about this, it seems a bit awkward, but I do want to know how it goes and feels, so I’ll try it out once” ended up being “this is great, I’m doing it every day and loving it”. Here’s why you should try it and why it may make your life more awesome.

I found the Dvcs-autosync project on the vcs-home mailing list, which btw is a great list for folks who are doing stuff like maintaining their home directory in a vcs.
In short:

• simple python tool (600 sloc), works with your dvcs of choice (mainly tested/used with git)
• watches for inotify events, performs commits on changes (coalesces some changes together)
• synchronizes with other clones (remotes), uses xmpp for push notifications
• let’s you know what’s going on through libnotify popups or whatever
• home page: http://mayrhofer.eu.org/dvcs-autosync
• dvcs-autosync gitorious repo
• initial announcement on vcs-home

There are tons of articles describing how you can rewrite history with git, but they do not answer “why should I do it?“. A similar question is “what are the tradeoffs / how do I apply this in my distributed workflow?”.
Also, git developers strongly encourage/command you to write commit message in imperative present tense, but do not say why. So, why?
I’ll try to answer these to the best of my abilities, largely based on how I see things. I won’t get too detailed (there are enough manuals and tutorials for the exact concepts and commands).

== A library providing UI functions for shell scripts ==

When you write bash/shell scripts, do you write your own error/debug/logging/abort functions?
Logic that requests the user to input a boolean, string, password, selection out of a list,
date/time, integer, … ?

Libui-sh is written to take care of all that.
libui-sh is meant to a be a general-purpose UI abstraction library for shell scripts.
Low impact, easy to use, but still flexible.
cli by default, can optionally use ncurses dialogs as well.

Full article

pyblosxom is a pretty cool blogging platform written in python.
Like many of the modern minimal blog engines it works with plaintext files only (no database), has a relatively small codebase, supports many plugins (like markdown support), is written in a proper scripting language, has a simple and clean file structure, is seo-friendly, and so on.
The one feature that sets it apart from other minimal blog engines is that it supports comments, and doesn’t just rely on an external service like disqus, but stores comments as plaintext files as well.
Some features seem a bit overengineered (like, multiple possible locations to store themes (known as “flavours”) and templates; I’m a fan of convention over configuration and keeping things simple), but discussing this with the maintainer revealed this is because pyblosxom is meant as a reimplementation of the original perl-based bloxsom project. Over time features could be simplified and/or redesigned.
So I plan to migrate this blog from drupal to pyblosxom.
To do this, I’m building the tool drupal-to-pyblosxom.
The goal is to convert posts, associated metadata (publish time, tags) and comments from the drupal database to pyblosxom files. Source code display should be converted too (merely a matter of converting between different plugin conventions), and images shown should be downloaded. Currently I’m about halfway, if there’s anyone out there with a similar use case, help is welcome ;)

When cleaning up a system and going over git repositories I often wonder if a git repo contains any interesting, but unpushed work. (i.e. “unique” content)
I heard bzr (or was it hg…) can do it out-of-the-box, but I couldn’t find any existing solution for git.
So I wrote a script to do this. It checks a repo for unique commits, tags, branches, dirty files/index, added files, or stashed states. In comparison to a specific remote, or all of them, and uses an appropriate exitcode.
git-remote-in-sync.sh
The script is part of a bigger git-scripts repo (most of the scripts written by random people). Although the original repo creator hasn’t gotten back to me this seems like a good starting point to have some sense of order in the wildspread of git scripts.

Here are some other scripts I find pretty useful:

In light of the work and discussions around supporting Nilfs2 and Btrfs on Arch Linux and its installer AIF,
I’ve shared some AIF filesystem code design insights and experiences on the arch-releng mailing list.
This is some hard to understand code. Partly because it’s in bash (and I’ve needed to work around some limitations in bash),
partly because there is some complex logic going on.

I think it’s very useful material for those who are interested (it can also help understanding the user aspect),
so I wanted to share an improved version here.
On a related topic: I proposed to do a session at Fosdem 2011/“distro miniconf” about simple (console based) installers for Linux,
and how multiple distributions could share efforts maintaining installation tools, because there are a lot of cross-distribution concerns
which are not trivial to get right (mostly filesystems, but I also think about clock adjustments, bootloaders, etc).
Already several distro’s use the (or a fork of) the Arch installer, for example Pentoo,
but I think cooperation could be much better and more efficient.

Anyway:

As of yesterday, Brendan ‘bct’ Taylor is the new Uzbl project leader / maintainer.
Yesterday I did the newspost on uzbl.org which explains the reasoning. I can add it feels pretty weird “giving away” and “leaving behind” a project you spent so much time on and which grew a large (well, for a FOSS side project with a hacker audience) base of users and contributors, and which served as inspiration for various other projects.

Background info:
I’m currently in the process of evaluating (V)PS hosting providers and backup solutions. The idea being: I want a (V)PS to run my stuff, which doesn’t need much disk space,
but in the meantime it might be a good idea to look for online backup solutions (oops did I say “online”? I meant “cloud”), like on the (V)PS itself, or maybe as a separate solution.
But I’ve got some diverse amount of data (my personal data is mostly a lot of small plaintext files, my mom has a windows VM for which I considered syncing the entire vdi file)
At this point the biggest contenders are Linode (which offers quite some flexibility and management tools, but becomes expensive when you want extra disk space (2$/month*GB), Rackspace backup gives you 10GB for 5$/month, but they have nice backup tools so I could only backup the important files from within the windows VM (~200MB), and then there’s Hetzner, which offers powerful physical private servers with a lot of storage (160GB) for 29eur/month, but less flexibility (I.e. kvm-over-ip costs an extra 15eur/month)

Another issue, given the limited capacity of Belgian internet connections, I needed to figure out how much bandwith rsync really needs, so I can calculate if the duration of a backup run including syncing the full vdi file is still reasonable.

I couldn’t find an rsync benchmarking tool, so I wrote my own.

Features:

• simple
• non invasive: you specify the target and destination hosts (just localhost is fine too), and file locations
• measures time spent, bytes sent (measured with tcpdump), and data sent (rsync’s statistics which takes compression into account)
• supports plugins
• generates png graphs using Gnuplot
• two current plugins: one using files of various sizes, both randomly generated (/dev/urandom) and easily compressable (/dev/zero), does some use cases like initial sync, second sync (no-op), and syncing with a data block appended and prepended. The other plugin collects vdi files from rsnapshot directories and measures the rsyncing from each image to the next

Rss2email is a great tool. I like getting all my news messages in my mailbox and using smtp to make the “news delivery” process more robust makes sense.
However, there are some things I didn’t like about it so I made a github repo where I maintain an alternative version which (imho) contains several useful improvements, both for end users and for developers/downstreams.
Also, this was a nice opportunity for me to improve my python skills :)

Here is how it compares:

Being active as both a developer and ops person in the professional life, and both an open source developer and packager in my spare time, I noticed some common ground between both worlds, and I think the open source community can learn from the Devops movement which is solving problems in the professional tech world.

For the sake of getting a point across, I’ll simplify some things.

First, a crash course on Devops…

Dusty Phillips, Arch Linux shwag guy, Archcon co-organizer, (python) consultant and since recently buddy of mine wrote his first book: Python 3 Object Oriented Programming.

I got the opportunity to get a free pdf copy in exchange for a review on my blog, so here we go.

I’m back from Canada/Archcon, and it was great. I’ve been in Toronto for 11 days, and visited Montreal for 3 days.

Archcon

Archcon was small (20-ish people). (That’s what you get for doing it in Canada ;), but very nice.
Interesting talks, informal, good vibe, decent logistics and catering.
This year it happened because Dusty and Ricardo actually just wanted to have a conference without worrying too much about the attendance,
next year we should do it again because Arch (conferences) rock(s), and because we need more visitors. More central locations such as Seattle and Europe have been suggested.
Either way, next year both Judd (founder) and Aaron (current overlord) should be there. (this year they both had lame excuses like family reunions and “almost getting married”. Congrats btw, Aaron!)

It was an absolute pleasure to meet some more of my fellow devs, and users.
Here is a pic from the group (unfortunately, a few are missing)

As mentioned earlier, I’ll be at Archcon in Toronto in a few weeks.
It’s a very small conference, and the first of its kind. At the last FrOSCon we have been playing with the idea to hold an informal Arch conference in Europe, but those were just ideas. Dusty and Ricardo beat us with an actual implementation.
This is great, and one of the milestones in Arch Linux history. Which is why I want to be there and help making it better.

I recently did two talks, for which the videos are now online.

• Uzbl lightningtalk @ fosdem 2010
• Open Source Monitoring tools lightning talk @ Kangaroot showcase 2009. This one is password protected. If you were a participant, you should have received the pass

If all goes well, I’ll be at ArchCon this summer, where I’ll be doing these talks:

• AIF: The Arch Installation Framework
• Uzbl & web interface tools which adhere to the unix philosophy. Whereas in the fosdem talk I had to focus a lot of information into a short timeslot, here I’ll elaborate a bit more

We’re not sure yet if those talks will get videotaped.

In november last year, I was contacted by Facebook HR.
They found my background interesting and thought I might be a good
fit for an “application operations engineer” position in Palo Alto, California. (it is
basically the link between their infrastructure engineering and operations/support
teams).

I’ll be at fosdem - 10th edition - again this year.

I’ll be presenting a lightning talk about uzbl.
Also, Arch Linux guys Roman, JGC, Thomas and me will hang out at the distro miniconf. We might join the infrastructure round-table panel, but there is no concrete information yet.

More stuff I’m looking forward to:

When you use rrdtool, it can happen that you first create your databases, then collect a whole bunch of data and decide later you want more accuracy/longer periods.

You probably know you can resize primary partitions by deleting them and recreating them, keeping the starting block the same but using a higher block as ending point. You can then increase the filesystem.
But what about logical partitions? A while back I had to resize an ext3 logical partition which ended at the end of the last logical partition. I learned some usefull stuff but I only made some quick scratch notes and I don’t remember all details so:
Do not expect a nice tutorial here, it’s more of a commented dump of my scratch notes and some vague memories.
The information in this post is not 100% accurate
I wondered if I could just drop and recreate the extended partition (and if needed, recreating all contained logical partitions, the last one being bigger of course) but nowhere I could find information about that.

So I’m back from the 3-day maemo summit in Amsterdam. It was very nice. Very well organized, and Nokia definitely invested enough in catering, fancy-suited people and such to please all 400 of us. I met several interesting people, both from the community, as well as Nokia guys.
The talks were diverse, but interesting (duh?). I will especially remember the kickoff with its fancy visual effects and loud music that set the mood straight for the entire weekend.
The best moment was, of course, when it was announced that every summit participant would receive a n900. Uncontrolled hapiness all around.

Xfce/Gnu/Linux works amazingly well on my moms workstation, with one exception: opening files automatically with the correct program.

The two biggest culprits are:

• Gtk’s “open file with” dialog: if any Gtk program doesn’t know how to open a file it brings up this dialog that is horrible to use. You can search through your entire VFS for the right executable. No thumbnails, no usage of .desktop files, $PATH, autocompletion and not even limiting the scope to directories such as /usr/bin
• Mozilla software such as Firefox and Thunderbird: they only seem to differentiate files by their mimetype, not by extension. There are add-ons to make it easier to edit these preferences, but eventually you’re in a dead end because you get files with correct extensions but unuseful mimetimes (application/octet-stream)

Luckily the fd.o guys have come up with .desktop files.

Inspired by Snippy and snippits, I wrote a simple tool called snip.
It helps you to automatically fill in text for you (which can be dynamically created) and/or to perform custom keypresses and operations.

Fbcmd is pretty cool.
I quickly hacked this script together which pulls all photo albums from friends on facebook, so I have them available where I want. (It should also pull your own albums, but I don’t have any so I can’t check that)

I’ve been playing with Zenoss (2.4) for the first time. Here are my thoughts:

I need a browser that is fast, not bloated, stores my data (bookmarks, history, account settings, preferences, …) in simple text files that I can keep under version control, something that does not reinvent the wheel, something that I can control.

Well, I could not find it.
So I started the uzbl browser project.

I wanted to know how responsive dmenu and awk, sort, uniq are on a 50MB file (625000 entries of 80 1-byte chars each).

Yesterday I finished the first working version of AIF's automatic procedure, along with a sample config for a basic install..

For me personally this means I can start working on the next step towards my goal of having all my systems "metadata" centrally stored (along with my real "data"), and the possibility to reconstruct all my systems in a deployment-meets-backup-restore fashion ( see rethinking_the_backup_paradigm_a_higher-level... )

At my new job, I’m writing a quite full-featured web application.
I’ve choosen to use CakePHP.
Why? Well, it may be 2 years since I last used it, but I’ve followed the project and it’s planet, and it seems to have matured and gained even more monumentum.
I want to use something that is widely used so there is plenty of stuff available for it, it’s RAD, it’s flexible and powerful.
I noticed things such as CLI support and documentation have improved tremendously too.

However, I find that still, the recommended (or at least “most commonly used”) practices are not as efficient as they could be, and that emphasis is placed on the wrong aspects.
See, even though the bake tool has come a long way since I last used it, it’s still used to “generate some standard models/controllers/views” and the developer can take it from there [further editing the resulting files himself].
Finetuning generated code by editing the templates (in fact, only views have templates; the php code of models and controllers is hardcoded in the scripts that generate them), is still an obscure practice…
Also, there are very few commandline switches (Right now you can choose your app dir, whether you want to bake a model,controller or view, and it’s name.)
All other things (validation rules, associatons, index/view/edit/add actions/views, which components, overwrite yes/no etc) are all handled interactively.
There are also some smaller enoyances such as when you specify one option like the name of the model, it assumes you don’t want interactivity and produces a model containing nothing more then the class definition and the membervariable $name, which is usually worthless.
One thing that is pretty neat though, If you update $this->recursive in a model, the baked views will contain stuff for the associated things. But so much more could be done…

My holidays present for Arch devs and users: AIF alpha-0.6 !

* Changes since alpha 0.5:

When you’re stuck on a problem, or not even stuck but you just want to boost your creative/out-of-the-box thinking…
Take a shower. When I’m thinking about a problem and I take a shower, the ideas and thoughts just start popping up, one after each other, or sometimes even two at the same time. It’s amazing. And it works every time.

Recently I started thinking about writing my own automatic installer that would set up my system exactly the way I want.
(See rethinking_the_backup_paradigm_a_higher-level…)

I looked at the official Arch install scripts to see if I could reuse parts of their code, but unfortunately the code was just one big chunk of bash code with the main program and “flow control” (you must first do this step, then that), UI-code (dialogs etc) and backend logic (create filesystems, …) all mangled up and mixed very closely together.
Functionality-wise the installer works fine, but I guess the code behind it is the result of years of adding features and quick fixes without refactoring, making it impossible to reuse any of the code.

So I started to write AIF: the Arch Linux Installation Framework

I couldn’t find a standalone application/script that implements freedesktop compliant (XDG based) autostarting of applications, so I decided to write my own.
The project is at http://github.com/Dieterbe/dautostart .

Right now, all the basics seem to work (except “Autostart Of Applications After Mount” of the spec).
It’s probably not bugfree. I hacked it together in a few hours (but it works for me :-). Bugreports welcome!

Put this in your .bashrc, and the current directory in your PS1 will be printed green if the previous command had exit state 0, red otherwise. No more typing ‘echo $?’, ‘ && echo ok’, ‘|| echo failed’ etc on the command line.

I’m managing my ~ in svn but using gnome & gconf makes this rather hard.
They mangle cache data together with user data and user preferences and spread that mix over several directories in your home (.gconf, .gnome2 etc).
The .gconf directory is the worst. This is where many applications store all their stuff. User preferences but also various %gconf.xml files, which seem to be updated automatically everytime ‘something’ happens: They keep track of timestamps for various events such as when you press numlock or become available on pidgin.
I’m fine with the fact they do that. I’m sure it enables them to provide some additional functionality. But they need to do it in clearly separated places (such as xdg’s $XDG_CACHE_HOME directory)

DDM v0.4 has been released.
Since the last release many, many things have been changed/fixed/added.

I’ve put my (somewhat interesting) projects on GitHub.
Git is a damn cool VCS for distributed development, and I think Github integrates with it really nicely, adding some useful aspects for following and collaborating on projects.
The projects I have migrated to my GitHub profile are:

Often while you’re occupied with something, some thought pops into your head. Something that you want to remember/do something about.

I’ve been reading GTD lately and it’s absolutely a great and inspiring book.
Having made my home office space into a real Zen I want to start implementing GTD in my digital life but it seems very hard to find a good GTD tool that fully implements GTD. (even though there are a lot of tools out there)

The most interesting ones (each for different reasons) I’ve looked at so far are Thinkingrock, tracks and yagtd (the latter requiring most work before it does everything I need, but it’s also the most easy to dive into the code base). I’m keeping my eyes open because there are certainly more things to discover.

Even though there are probably no applications out there that can do everything I want, I just wanted to share my feature-wishlist. These are the requirements I find that a really good tool should comply with:

In this post I explain my vision on the concepts of backups and how several common practices are in my opinion suboptimal and become unnecessary or at least can be done more easily by managing data on a higher level by employing other patterns such as versioning important directories and distributed data management.

For a while now I am typing using solely the Dvorak keyboard layout. I roughly estimate it has been 4 or 5 months now - with the first month being a pain in the ass because i had to relearn typing pretty much from scratch - but now my typing speed is starting to exceed what it used to be in querty, and I still have much headroom to improve.

For those who have no clue what I’m talking about: think for 30 seconds which characters you type the most and which the least (eg: which characters occur the most/least in the language you type?).

Ok you got them? Now look at your keyboard and spot where these characters are. Now consider where your fingers are most of the time (if you’ve never learned to type: the ‘base position’ for your fingers is on the middle row). Notice anything strange?

On 31-3-2008 LCL, one of the most used datacenters in Belgium - and the only one with a 0% downtime record in Belgium - had major power issues with their datacenter in Diegem, bringing lots of Belgian parties offline. (more specifics on the net).

If you’re one of the sysadmins of a website with 35M members and 150M hits per day this means you’re in for an exciting night …

UPDATE: this information is outdated. See http://github.com/Dieterbe/ddm/tree/master for latest information.

Introduction

If you have multiple sets of data (e.g.: music, images, documents, movies, …) and you use these on more then one system ( e.g. a laptop and a file server) then you probably also have some ‘rules’ on how you use these on your systems. For example after capturing new images you maybe put them on your laptop first but you like to sync them to your file server frequently. On the other hand you also want all your high-res images (stored on the server) available for editing on the laptop, and to make it more complicated you might have the same images in a smaller format on your server (for gallery programs etc.) and want these (or a select few albums of them) available on the road.

The more different types of data you have and the more you have specific work flows the harder it becomes to keep your data as up to date as possible and consistent on your boxes. You could manually rsync/(s)cp your data but you end up in having a mess (at least that’s how it turned out on my boxes). Putting everything under version control is great for text files and such, but it’s not an option for bigger (binary) files.

I wanted to keep all my stuff neatly organised in my home directories and I want to create good work flows with as minimum hassle as possible, so I decided to write DDM: the Distributed Data Manager.

If you serve lots of (small) files with Lighttpd you might notice you’re not getting the throughput you would expect. Other factors (such as latencies because of the random read patterns ) aside, a real show stopper is the stat() system call, which is a blocking system call ( no parallelism ). Some clever guys thought of a way to solve this : a fastcgi program that does a stat(), so when it returns Lighty doesn’t have to wait because the stat information will be in the Linux cache. And in the meanwhile your Lighty thread can do other stuff.

I wish I could put this on my webpage :

I’ve been thinking about how a specific bash history for each directory could improve productivity, and unlike what I feared it was actually pretty easy to find a solution on the net.

I forgot the username and password to access the web panel of my router.
Luckily I knew some possible usernames and some patterns that I could have used to construct my password, so I just had to try all the combinations… Too much work to do manually but easily done when scripted.

Here is the php script that I came up with. (obviously stripped of my personal stuff). It got my account in less then a second :)

Phew! where to start? Probably at this blogpost. It’s about making it very easy to work with external encrypted volumes. I’m not going to talk about the article itself but about a great tool i discovered thanks to it: Zenity.

Ever needed to use arrays of two or more dimensions but got stuck on Bash limited array support which provides only 1 dimension?

There is a trick that let’s you dynamically create variable names. Using this, you can emulate additional dimensions.

FOSS is written by users, for users, and what I’ve been doing/experiencing this afternoon is a perfect example of that.

I just upgraded this site to Drupal 5.2. The package came with upgrading instructions consisting of 11 steps to complete the upgrade proces, but after reading it a few times I realized it could be done easier.

I’m afraid the time has come to say goodbye to CakePHP, and to the projects I’ve been working on for it.
I still like Cake … In fact, the further development of 1.2 goes the more I like it (well, generally spoken that is … because there are some minor things I don’t like but that’s not important now). The truth of the matter is I like to develop, I like the php language and I enjoy working with Cake.
But .. all the sites I currently work on are all community sites or blogs

I’ve always liked Amarok: it does everything I always wanted, and more. It looks perfect in every way …
But .. it uses the QT library, and although there are tricks to make QT applications more fit in with your gtk desktop/theme it will never fit in perfectly, not only graphically but also because you still need to load the qt libraries when you want to listen to some music and it is built to interact with the KDE desktop environment.

So, I’ve been looking for an alternative, a GTK application strong enough to actually be able to replace Amarok, the king of all software music players.

You probably already heard of Google Analytics. It’s a pretty nice program that (basically) gathers data about visits of your site and creates reports of it. It works by including some JavaScript code on your page, so that each page request triggers a call to the Analytics tracker sending along some data such as which page is requested and which resolution was used. (no personal or other privacy-sensitive data is sent). But here is the deal! I just discovered that you can also track events that don’t require page requests!
Think of links to files or to external locations, JavaScript events (Ajax anyone?) or even Flash events (but who is crazy enough to use Flash anyway?).

I just watched Cory Doctorow’s talk which is part of the Authors@Google series on youtube.

He made some great points about where the (music) industry gets/does it wrong and about some fundamental flaws in our law systems (especially with regards to copyright). All of which are of course results of the challenges imposed by the “information age”.

Introduction

During the development of my thesis I wanted to create a drag ‘n drop interface. But I never did anything like that, I never used CakePHP’s Ajax helper and neither made I ever use of more advanced functionalities of Scriptaculous/Prototype. Hell I even never touched Ajax before this!

Although there are some basic CakePHP/Ajax tutorials out there, I still had a hard time because some knowledge about Ajax (in CakePHP) was assumed in all of those. After a lot of googling I even found a tutorial called CakePHP: Sortable AJAX Drag & Drops - The Basics
“Perfect!” I thought, until after staring at the article for a long while and I started to notice nowhere in the article “$ajax->drag”, “$ajax->drop” or “$ajax->dropRemote” is used. (those are calls on the CakePHP Ajax helper to enhance objects to become draggable, or to become a dropbox where draggables can be dropped into). So the only more or less suited tutorial about drag ‘n drop was actually about sorting and didn’t use the drag/drop function calls at all. Even though it contains very useful information.

Long story short: I finally got it working (thanks to Krazylegz and kristofer and possibly others too, it has been a while so I may forget someone ;-), and learned a lot in the process. I will share what I learned with you guys so that hopefully it’s a bit easier for you then what I had to go through.

Yesterday, after a night of searching and fixing spelling errors, things that could be better explained and other small details,
I got my thesis printed and delivered the six books to my school.

I just signed my contract at Incrowd, the company behind sites such as redbox and facebox.

I will be working there in a team of all young, enthusiastic people. Among those, some people are already familiar to me: my old friend Lieven (we’ve played in a band together but kept in touch afterwards) and my ex-classmate Jurriaan. Both of them love their jobs btw :-).

My official title is “System & Network architect”.
Things I will be doing there is

From the very little experience I have with Debian, and from the stuff I’ve been reading about it, I think I can safely say Debian has always been a special distribution: packages always take very long to get into the stable tree, because Debian wanted to be a rock solid system where packages go through a lot of testing. (“We release it when it’s done”) The end result is a distro where you don’t have the latest software, neither as much flexibility as, say Gentoo or Arch: You’d many times need to adapt your way of doing things to the “Debian way” (or be prepared to look for help in really obscure places and probably break things) but the end result is a stable distro where everything works very decently. That, combined with no licensing fees (unlike for example Red hat), make it the perfect choice for a server in small companies, where money is more important then features such as professional support or official certifications.

However, it seems like Debian is taking a route that will make it lose it’s advantages over other distributions in the server market:

In the Cake community, there has always been much interest in authentication/authorization systems. The issue of authentication has been addressed in several add-ons provided by the community, such as DAuth (written by me), OthAuth (written by Crazylegs) and many others.

However, one of the additions to the 1.2 branch which is currently in active development , is a built-in auth module. A module that isn’t finished yet but it sure is worth it looking at. (In fact I’m thinking about making a new dAuth version built on cake’s own auth system.). As most bakers know, there is very little information about the 1.2 branch in general, and the auth component in specific. So what I will try to do, is delve in the code, mess with it, and explain my findings in this post.

Dit weekend (17-18 maart) ben ik naar Kwartee 4 geweest.
Kwartee weekends worden georganiseerd door Formaat (vroeger bekend als VFJ) en ging door in vormingscentrum destelheide te Dworp (dichtbij Halle, ten zuiden van Brussel).
Twee man sterk (Steven en ik) vertegenwoordigden we jeugdhuis SjaTOo.

Every year, during a special weekend in February, the University Libre of Brussels suddenly becomes a little more geeky.
It's that time of the year when many European (and some inter-continental) colleagues join us at
Fosdem: the Free and Open source Software Developers' European Meeting (more info here).