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the fatal ways of the sheevaplug

tags: hardware 2010-07-17 19:56 by lhw

It’s been about 10 month now since I ordered 7 SheevaPlugs, a plug sized computer, from GlobalScale. Everything ran smoothly for the next months till about 2 weeks ago when it suddenly became unresponsive and spammed the network with packages slowing down my other clients. A few more days later and it broke down completly with a blinking green LED. As it turned out this was already the second dead SheevaPlug after the one sre got back then.

After just about 1 minute search you will find the following thread on plugcomputer.org, the official forums: Is my sheevaplug dead ???. After reading the thread for a while it was obviously the power supply units fault. Seeing some of the pictures its a miracle that thing worked in the first place. The average lifetime of the PSU is about 9 month according to the thread. NewIt.co.uk the british GlobalScale reseller even offers the PSU as single product nowadays.

I first thought about buying on of those but then I probably would have gotten the same faulty PSU again. So I tried locating the defect parts on my one. I replaced an electrolytic capacitor and checked the output under stress with a 12cm fan, which seemed to work. But not when connected to the SheevaPlug which seems to suck that PSU to its uppermost limit. So there were more faulty parts which I couldn’t locate beneath all that brownish/blackish glue.

In the end I removed the internal openframe PSU and connected it to an cheap external power supply. As board connector the plug from an old PC case speaker fits perfectly.

And here some pictures of the now again working SheevaPlug:

migrating jabberd2 to ejabberd

tags: ring0, services 2010-04-27 08:30 by lhw

After being constantly pelted to change our Jabber/XMPP services from jabberd2 to ejabberd. We took a few hours of time and gone through with it once and for all.

“Thats gonna be easy”, was our first thought on it, “There are merge tools and such”. After testing the tools and running into problems with each of them(not merging at all, producing garbage output), we simply converted the information presented in the jabberd2 database to a ejabberd compatible format. Here is the sql we used to convert our database format: git.ring0.de

Okay the next problem was way worse then the first one. jabberd2 uses UNIX crypt() with salt for saving the passwords where as ejabberd uses plain text passwords by standard, hashes with hacking. As we are not really good with an old language like erlang we hacked ourselves something together. Mainly relying on the features (My)SQL provides us with. And here is the patch against ejabberd 2.1.2: git.ring0.de

Of course this version of the patch requires you to use MySQL with ejabberd therefore relying on the module from ejabberd.im But from this point on it’s easy to patch yourself some SQL together for other servers as well.


tags: ring0 2010-03-21 21:43 by lhw

Welcome to a side product of ring0 development.

As our C version of our blog software is halted for now I took the opportunity, and fixed us up with some Vala CGI. Which is basicly displaying you nicely formated text files.

What this blog is all about is very simple: Displaying our progress in certain fields of development and solutions for uncommon issues with software. Also code snippets.

Have a nice day folks