Archive for September, 2008

Energy numbers

Sunday, September 28th, 2008

Both solar and nuclear are hitting the news with advances in efficiency and utility. CEO of Hyperion Power Generation interviewed about the Uranium Hydride reactor provides some numbers that yield scope and scale in thinking about energy sources.

  • specifically designed to fit on the back of a flatbed truck at about 20 tons weight and a meter and a half wide by 2 tall.
  • reactor life is 8 – 10 years with 70 Mw thermal or 30 Mw electrical output at about $100 million each. That appears to be about a nickel per kWh.
  • certified ‘walk a way’ design does not need continuous operator monitoring or attention
  • expected factory output is 400 reators per year or 10-12 Gw output – that’s like building more than 10 typical major sized power plants every year. The estimated market opportunity is for half a million of these units.
  • “The waste that comes out of our reactor after powering 20,000 homes for 8-10 years is about the size of a football.”

That’s a pre-packaged solution for powering a 20,000 home community for near ten years.

Posted in Off Grid | No Comments »

Ebox and the Samba share linked file problem

Thursday, September 4th, 2008

File sharing services are perhaps one of the most common uses for a network services box. Samba allows sharing files using the Microsoft Windows methods. It does a good job meshing the Linux ideas and Windows ideas – most of the time. Sharing a linked file has a problem, though.

eBox puts its Samba shares in the /home/samba/… and doesn’t allow tinkering with the samba configuration files. This means that, if you have a file or folder somewhere else, you have to use a link to have it appear in your shared files folder.

If you have the Samba Unix Extensions enabled, which they are by default, a Linux client won’t be able to access files on that share through the link as it sees the link as being local. To fix this, you have to disable the Unix Extensions. See the bug report at contribs.org.

The Unix Extensions allow users to set their own file permissions and such things. Since eBox won’t allow tweaking the server configuration file to turn them off, you need to turn them off when you mount the share on the client. The key option to use is ‘nounix’ as in the following example:

sudo mount.cifs
//serverIPaddress/sharename localmountpoint
-o user=workgroup/userid%password,
noperm,file_mode=0666,dir_mode=0777,nounix

Posted in Networks | No Comments »

eBox as an Ubuntu server front end

Thursday, September 4th, 2008

Trying to get a handle on all of the interconnected network services can be a challenge. It appears that the Canonical folks have decided that eBox is a good place to start and eBox provides a custom version of the Ubuntu server CD image with their software ready to go.

There are other FOSS options to provide a front end for services on a network box. Webmin is a good example.

Webmin is a web-based interface for system administration for Unix. Using any modern web browser, you can setup user accounts, Apache, DNS, file sharing and much more. Webmin removes the need to manually edit Unix configuration files like /etc/passwd, and lets you manage a system from the console or remotely.

These network administration front ends do not depend upon a GUI on the server. Instead they use the web server so you can administer your network from anywhere on the net.

A key difference between eBox and some of the other network management tools is how much they do for you. Do they just provide a front end for the various service configuration files and let you have at it or do they help you with the interdependencies between services?

eBox chooses the integrated approach which is probably why the Canonical folks tend to favor it for Ubuntu. This means that you have a bit less control about the configuration but when you set up a service, any others needed to make it work are also adjusted as needed. For instance, set up a Samba file server and the firewall rules are changed to allow that sort of activity.

In order to manage this integration, eBox maintains its own templates for the various service configuration files. At boot, it reads these templates and re-writes them so the services will be configured to a known state. This means that if you go tweak a service configuration in the usual way, that tweak will get lost the next time you boot the computer. If you just gotta’ tweak, you will have to find the eBox templates and tweak them. These templates are XML files in the eBox application folder.

eBox makes for an easy to set up network server with all of the services normally needed for a small business office. It doesn’t take much know-how to get it up and going with the services you need. Once you have a functioning server, you can explore and learn by testing things out and perusing the configuration files. It is a good lab platform for learning about network administration as well as a good resource for someone who needs a service box but not the usual hassle.

Posted in Networks, Systems | No Comments »