fast ramblings of a mostly technical nature.
Background I have a solar inverter made by Fronius that uploads json to an ftp server every ten seconds. There are two different json files (*.powerflow and *.interverter) with slightly different information. Every day, this means there are about 10k files and the file sizes vary but are usually between 500-1000 bytes each. On the local filesystem that equates to about 40MB per day. Over a year,…
For reasons I don't care to defend, my internet connection looks something like this: Since my firewall is connected to the hotspot via WiFi, bridging to my internal network is out of the question . While there are many tutorials and approaches to getting IPv6 into a topology that looks like this, none of them work for me for various reasons. eg: the hotspot will not delegate a prefix via dhcpv6 I…
If you are like me, you enjoy breathing. Perhaps you are not as keen on it but you certainly notice when it starts getting uncomfortable to breathe from heavy smoke or smog. After the latest round of California wildfires, I decided to purchase a PurpleAir sensor so I could know how the air inside my house and outside of my house were likely to affect me. I also have no central AC so understanding…
Everytime you download a tar.gz, Zod kills a kitten. Everytime you generate a tar.gz, well, let's keep this family-safe. In 2015, there should be very few reasons to generate .tar.gz files. We might as well just use .zip for all the progress we have made since 1992 when gzip was initially released. xz has been a thing since 2009, yet I still see very little adoption of the format. Today, I…
It seems like the running community needs something along the lines of what the Hacker Manifesto was meant to be, except for running. There are many articles describing running to runners but perhaps this can be a document to introduce non-runners to runners... or even a document for runners to cherish. -- Hi, I am a runner. I may not run faster than you, but I might run a lot further . Or maybe I…
As I imagine many people to be, when bringing up hosts, I'm still stuck in the days of: Step 1: (node) configure networking Step 2: (node) configure the hostname Step 3: (service1) configure DNS to match Step 4: (service2) plug this into some form of configuration management Step 5: profit The problem is that you often have a complicated back and forth between configuration of the node and…
I live in a beautiful city that is practically ideal for runners in the winter. There are long flat areas to run as well as hilly and mountainous regions to train in depending on your goals. There is also an abundance of sunshine and ever so slight lack of oxygen at 2500' above sea level. To clarify, it's an ideal place for winter training for an early spring marathon since the summer gets pretty…
I have looked around for good information on images and support for sparse storage and compression. After experimenting a bit I decided to compile a few key results. There are two attributes I care about here: storage and network transfer. In order for efficient storage of an image, the image must be as small as possible. If there is a run of no data on an image (free space that has been filled…
Tonight, I found myself trying to implement the spice proxy out of curiosity in havana. I found a nice post that talked about how to do this after banging my head on the wall for a while: http://joshrestivo.com/?p=32 Anyway, this lead to getting " console is currently unavailable. Please try again later. Reload " when I tried to load a console of an already running host. I dove into the stack…
OpenStack is a conceptually neat piece of software. It's very distributed and fault-tolerant and loosely coupled. That also means that getting back meaningful errors can be a tough process when something goes wrong. Today, I upgraded my development cluster from Grizzly to Havanah. I spent several hours understanding new and changed config options throughout the landscape and updated my puppet…
I've been spending the last year poking and prodding OpenStack in hopes of having a management layer for the various hosts with instances throughout my data center. OpenStack has so many neat little bells and whistles and ... green developers. My DC is pretty well established and so I need to be careful about introducing new technology. I'm amused at the toy that is devStack. It seems to be the…
Background: A colleague and I are developing a piece of code (called pbsmake) in python that ends up interpreting something that looks like a Makefile. We will use pbsmake to help distribute jobs to a local scheduler (each makefile target gets its own job) but we found that we may want to use the pbsmake interpreter as a shell interpreter itself so we can simply execute certain commands (which are…
I have a small cluster of different hardware running Debian squeeze/wheezy and several machine have been really simple to setup with bonding (aka: trunking/link aggregation/port trunking/ ... the list goes on) using mode=4 or "IEEE 802.3ad Dynamic link aggregation". My final clue to solving the problem was some dmesg output: [ 14.777381] e1000e 0000:06:00.1: eth0: changing MTU from 1500 to 9000 […
If you are like me then you hate doing the same thing over and over ... which means you like to automate these kinds of processes when it makes sense to do so. I wrote a Blender plugin that imports a HiRISE DTM directly into Blender 2.5x and allows you to easily make fly-throughs of the various Mars locations that a DTM exists for. My work wants to make automated fly throughs with a trivial piece…
In working with IPv6 I've come to realize that there are a lot of funny defaults out there. The most basic of them seems to be in how to bind to a port. Simple? Yeah ... or so I thought. Under some versions Linux if you are to just listen on, say, [::]:80 then people connecting to your site via IPv4 might be logged as ::ffff:192.0.32.10 which is an IPv4 mapped IPv6 address . This means that…
From yesterday's post I took off and started researching ways that NFS over UDP can go wrong. I am now sufficiently scared away from ever writing/appending files on NFS that is using UDP. There are references everywhere to potential data corruption but only a few good sources that will give me anything concrete on the topic. Those references seem to be a bit outdated but the cautious…
I have found many places that will state that NFS over TCP is not appreciably slower on Linux unless you measure carefully. In fact, I found so many of them that I took it for granted for a while... until today. Here is the backstory (circa 2005): We are an NFS shop scaling to meet the demands of HiRISE image collection/planning/processing and we are having severe problems scaling our NFS servers…
I've been using IPv6 since I was asked to work on a project relating to it in 2002. At the time it was a cool "new" protocol to play with and had some really neat auto-configuration features. I deployed it in only small limited sites where I could view the old animated IPv6 turtle. More recently I have been using IPv6 in production and have seen a lot of attempts at making political grabs on IPv6.…
Given that I'm compiling Gentoo Prefix on a 2.3Ghz Linux host and it is taking several hours I started imaging how much work the computer is actually doing. 2.3 Ghz = 2300000000 cycles per second. Assuming we only use 10% of the CPU because we are waiting on I/O we are still talking 230000000 cycles per second. Each cycle represents a very small operation and perhaps only 10 little operations make…
Each new year brings oodles of expectations including the dreaded/coveted "new years resolution." My resolution is actually a meta-resolution and it is "to not need resolutions next year." If I live well enough from day to day then I don't need a special date to make my life better. Cheers!
Home: http://www.physicsfactory.org This is an interesting phenomenon with a bus-full of great demonstrations and wacky physicists who put on a great show and engage the audience with wonderful results! I spent a bit of time with the gang in the earliest days and have been pleased to see their successes grow. It seems that they are starting to look at accomplishing one of their earlier goals of an…
f1r2t b10g! .. ok, maybe I'm a little late in the game for that one but it's MY first anyway. For lack of a specific topic, this will be about interesting things I come across with a small'ish splash of my own thoughts. Enjoy! ;)