Monthly Archives: December 2008

Speed Up Multiple SSH Connections to the Same Server

Don Marti writes at linuxjournal about howto Speed Up Multiple SSH Connections to the Same Server.

This seems very usefull – so enjoy.

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Filed under System Administration

CTRL+A in OpenOffice.org Impress doesn’t behave as expected

I don’t have any reasonable explanation why does CTRL+A in Impress is mapped to the Open window (same as file-> open). I was a bit surprised to get that windows while trying to select all the text.

I’d be happy to hear the real reason for this.

p.s.

It seems that I’m not the only one wondering about this issue.

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Filed under Openoffice.org

Why using Apache and mod_jk to redirect ports to Jboss/Tomcat ?

I’ve seen a lot of machines running both Apache with mod_jk just to redirect ports to Jboss/Tomcat or another Java application server. As most of the Java AS have a built in HTTP server and can “talk” with that protocol, I can just let them run on the web (80) port and save me the extra configuration and memory Apache needs.

While this solution works fine, we should bear some things in mind:

  1. This solution requires running the Java AS as root, otherwise it can’t use a port lower than 1024. Running as root have some security implications.
  2. This means we can’t run regular websites on the server, as everything is handled by the Java AS.
  3. We can’t use Apache to load balance the Java AS (if we have more than one)
  4. We can’t run several Java AS on the same machine.
  5. We usually keeps the control on the AS for the system administrator, while running the AS as a separate user lets us pass the control to someone else.

So after seeing all the disadvanteges of not using Apache and mod_kl, I decided it worth the extra configuration and memory (:

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Filed under Free software applications, System Administration

A virtual world

I have a friend which works as a DBA. She decided she wants to test some of application at home. She tells me she is run here windows application though wine which run on linux under a virtual machine on top of windows.

And me answer is WTF? How do you have time for all these technologies when I don’t even have time to use one of them.

Anyway, I was proud to hear she just utilize everything she can to get stuff working (:

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Filed under Free software applications, Proprietary software, Proud to use free software

kSar – Fixing bugs (almost) online

While working with kSar to visulize sar’s statistics, a friend found a bug with kSar.

Most IT people don’t think they can have access to the developers, I reminded my friend that we’re dealing with an open source application and we should report a bug or at least check the bug with the develpers.

He wrote a message in the kSar forums, and the answer, in the form of a new minor version came 4 hours later. We testing the fix and were very happy.

I can just hope all my bugs will be solved so quickly (:

So, please don’t be shy about your problems with free software. Most developers will be happy to get a good bug report and help you. I believe that’s specially true about developers of small applications who are just happy to hear people are using their software.

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Filed under Free software applications, Proud to use free software, QA stuff, System Administration

Visualizing SAR’s data

When you build a server architecture for a project, your often want to test the performance afterwards. That’s true especially when the only way to know the application needs is to test them.

Most distributions  already come with the needed tools to measure your performance of the operating system with tools like top, free, vmstat, iostat, mpstat and sar. The latter is usually configured to run periodically through cron to collect statistics all the time.

But when you want to analyze the data, creating a graph is much better way to do it. I found two ways to do that easily:

  1. Using kSar, which reads the sar files and lets you choose which graph to show. As this is a java application its platform independent and can be using everywhere.
  2. Using sar2rrd and RRDTool.

I used the first method as it lets the user creates the graphs with a GUI, and makes my life easier. kSar also support creating a PDF report from the raw data, and thus lets the user/me to send an easy report for others to review.

If you need to follow graphs for many systems over time, I would advise you to install Cacti, which collects the data and summarize it nicely with a web intreface.

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Filed under Free software applications, System Administration

Can everything except windows can be free software?

I got my hands on a laptop with Windows XP installed, and can do whatever I want with it, except deleting the windows. I decided not to have a dual boot on it, but to try and make it free software only (well, except the windows itself).

The main uses for the computer are surfing the web (browser only, not email), editting documents, watching videoes and being able to burn files.

The results for now:

  • Mozilla Firefox (browser) – set to be the default browser, and I also removed Internet Explorer (well, windows only removes the links to the software and not the software itself).
  • OpenOffice.org (productivity suite) – set the be the default application to the doc, xls and ppt files. Can also read OOXML format.
  • ClamWin (anti virus)
  • InfraRecoder (CD/DVS recorder)
  • VLC (video player)- set to be the default video player (including Microsoft’s file formats).
  • Sumatra PDF (PDF reader).

See “open source as alternative” if you want to find an alternative for a specific closed software.

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Filed under Free software applications, Proprietary software, Proud to use free software