I learned an important tip that I thought I should share with others who are considering Octopress with publishing to S3/Cloudfront. If the S3 deployment line in your Rakefile includes the s3cmd option for “–cf-invalidate” you should be aware that this will drive up your costs quite a bit. (3 guesses how I know this) I had about a years worth of expected CF costs in my first month because I didn’t understand what that was doing.
I’ve run my own hosted server for many years now. Originally it was just to have my own mail server but later I decided to start the blog using Wordpress. It’s great to have the control and flexibility to do whatever you want with a server.. but there are definitely some downsides as well. Wordpress is great.. but there are constant security issues to worry about and people attacking your server trying to hack it with automated tools. Customizing it has also never exactly been easy.. and it’s a huge code base that I don’t really understand.
So this new version of the blog is far enough along that it was time to turn it lose.
I’m living in a part of town that has no good option for broadband internet. That’s very annoying as in some parts of town you can get verizon fios.. and in most of the rest you can get Comcast which isn’t terrible. Where I am your big choice is a company called Broadstripe.. which is so bad even the employees blog about it. So with that I decided to try Clearwire.. the Wimax broadband provider.
I’ve been working on a big new project since just before the new year and it’s starting to take shape and generate useful results. I can’t give away too many details on how exactly it works but I wanted to share this with some of you who are also working in telecom. I was asked to develop a real-time system to identify toll fraud that would work for our entire voip carrier network that currently originates calls from 19 different countries for both residential, SMB, and wireless. For those who don’t know.. I spent a year working for another telecom software company helping to run and debug a call mediation and rating platform for a tier2 carrier. This experience was useful in that I was able to quickly develop a scalable, distributed processing framework while avoiding the cumbersome overhead I’ve observed in other systems. Continue after the jump for more details…
Now and then I’m called on to help interview candidates for linux admin/engineer slots and as I’ve been doing some of that lately I thought I’d share the way I go about doing a technical interview. This approach seems to work equally well over the phone or in person.
I was called on to provide a method of alerting from within nagios that was more active and direct than the usual use of email or SMS messages. So I came up with a simple way to have a nagios notification place a phone call to our off hours tier3 support line to report certain very rare but serious problems.
We have had a Power DNS recursing cacher deployed at one of our busiest sites for a few months now and I thought others might benefit from some real world performance info. This is running on some older hardware.. dual Xenon 2.8Ghz system with 4G of ram and the only job it’s doing is running this recursor. These three graphs tell the tale. The first shows that the system is handling peaks of about 3800 queries per second and that about 99% of those are being answered in a fraction of a millisecond. The second shows that cache hits are averaging about 70-75% and the third shows that it’s doing this work while using at most one quarter of the CPU. Add to those impressive performance levels that I’ve had zero issues since putting it in production six months ago.
This is an update to my initial posting last July. It didn’t take long to figure out the lead batteries were not going to cut it for the sort of high performance bike I had in mind. So shortly after I moved I replaced them with a LiFePO4 pack from Yesa. I got this straight from the manufacturer in China at a considerable savings over other similar quality packs from retailers here. I can only speak for my experience.. but the guys at Yesa were top notch to deal with and after more than 6 months putting their batteries to work I’ve had no problems. The Li pack is lighter and I relocated it for better balance on the bike. With a fresh charge on level ground it can sustain 40… but 35 is a normal top speed once you get past the first few miles.If I had it to do over.. I might go with a 72v setup and a motor with more windings. That would allow for lower power draw but still ample speed when you need it. Continue Reading for more technical details..