Cluster Computing 101
I just read your March 2005 “Extreme Linux” column on building a low-cost
Linux cluster (
http://www.linux-mag.com/2005-03/extreme_01.html). What are you running on it? I’m interested in clustering, but not quite sure about what applications are out there.
Amit Uttamchandani, via email
Extreme Linux columnist Forrest Hoffman replies: The little, inexpensive cluster was built to show how cheaply one could begin working with cluster computing. I have done some parallel cluster analysis on the mini-cluster, but I use it primarily to try out new software and cluster toolkits. I always say there’s no reason to build a machine unless you have a need for it, because the need should dictate its design. —Forrest
Global Warming… to the Penguin
The State of Wisconsin currently has a bill in the works (see
http://www.wisdems.org/index.php?display= ReleaseDetails& id=584499) to require all electronic voting machines to produce a printed ballot receipt and run on open source code. Both provisions are safeguards that the new technology works as it should.
To me, it should be a simple matter for a voter to select his or her candidates, receive a printed receipt, verify that receipt is correct, and then be able to log on to www.wherethehellismyvote.gov to verify that the online system has captured the ballot correctly.
Of course, I plan to make my representatives aware that this implies that the operating systems should be open source, too. The corporations that cry about opening their source have no idea how much better their software could be.
Steve Fox, via email
I want to share news of a little victory for open source software in Spain.
A Spanish attorney, José Mar’a Lancho of the Spanish Ombudsman-People Defender’s Office, has convinced the Ministry of Public Administration of Spain to rewrite the rules governing the acquisition of software and hardware in the country to be technology neutral.[ Prior to his suit, according to Lancho, all new projects stipulated the use of Microsoft technologies. — Editor]. The new rules will allow other companies to bid for business and protect the public from lock-in, especially since Microsoft products are often incompatible with competing products.
Luis Espa–ol Bouché, via email
Directory 911
I have been teaching operating systems for over twenty years and have run
into a real annoyance in Linux.
Old Unix systems allowed the command od –x. to give students insight into directory structures. However, I can’t get Linux to run this command no matter how hard I try. Given that Linux is open source, the code clearly reveals what’s in a directory, so it’s surprising that the command isn’t allowd.
Is there any way, short of modifying and recompiling the kernel, to dump
a directory file?
Ed Corwin, via email
Linux Magazine Editor-in-Chief Martin Streicher writes: If you have an Ext2 or Ext3 filesystem, you can use the debugfs command to dump the contents of any file on the system, including files that represent directories. An example is shown in the sidebar at right.
By the way, the <(“less than”)and >(“greater than”)characters in the dump command are literal: you must type them to identify the inode argument. I hope this helps. —Martin
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