Archive for March, 2008

Tips and tricks: Choosing the password hashing algorithm for /etc/shadow during installation

This is a new feature that has been requested in the Red Hat Enterprise Linux product line. The supported algorithms are DES, MD5, and SHA-256/512. They will be available after the upcoming updates releases as well as in Rawhide. The new algorithms will be configurable via Kickstart only. Here is the correct code. » Read more


Tips and tricks: In which languages can I receive JBoss Technical Support?

At the moment, JBoss Technical Support is available in English. Support for other languages may be added at a future time.

When transferring an existing Red Hat Support case in another language to JBoss Support, please be prepared to provide a description of the case in English for the JBoss engineer.
» Read more


Friday round-up

Welcome to Friday, our favorite day of the week. And here’s our handful of recent news we couldn’t resist sharing, to send you on your way into the weekend:

  • Don’t miss the New York Times piece on the passing of Gary Gygax (The flowchart is what really makes the article. We want the poster. Badly.)
  • The One Laptop is making waves in the Philippines.
  • Charles Chen has been in meetings with the Philippine Business for Social Progress (PBSP) to evaluate the XO, and comments:

    “This is to inform all the members of OLPC PH that I had met two weeks ago with the officials of the Philippine Business for Social Progress (PBSP), the country’s largest NGO in working in partnership in establishing an OLPC pilot to be done with the primary school level of the Don Bosco Technical College in Mandaluyong.”

    “PBSP can support OLPC PH by developing the needed governance practices we need to implement this program. At the moment, PBSP is currently evaluating the project requirements of this pilot as well as the possible use of the XO for its own educational program. Their program initially aims to provide about 20,000 laptops and will be a big boost to OLPC PH if they find XO suitable for their needs.”

  • Microsoft finally relents–IE8 will use web standards (like the rest of the world’s broswers, about time!)
  • Rumors have been flying around the virtual world for weeks that Linden Labs CEO Phillip Rosedale would soon resign, and today’s Second Life newswire confirmed it. There was no comment on associated rumors of an eventual IPO for the social networking/gaming platform.
  • And so far, NIN’s open release of their latest work is being considered a success, insofar as $1.6 million in profit is considered successful. Considering the cost to release through the digital channel was $38? Not bad. Not bad at all.

Video: Summit 2008 preview

Whether you’re a returning guest or a just thinking about attending, the Red Hat Summit is fast approaching. Check out this year’s Summit preview video, and when you’re done, hit the event website and get the details. We’d love to see you there. And get some chowda.

Download this video: [Ogg Theora]



» Read more


Tips and tricks: How do I set the real time scheduling priority of a process?

In the event that a process is not achieving the desired performance performance benchmarks, it can be helpful to set CPU affinity, real-time scheduling policy and real-time scheduling priority. Experimenting with different options using the taskset and chrt commands can help determine if this approach will provide the desired results.

The taskset sets CPU affinity for a process. The chrt sets real time scheduling options. The two commands can be used in tandem. For example:

taskset -c 2-3 chrt -f 1 <command>

The above usage would force <command> to run on CPUs 2 through 3, using the “fifo” scheduling policy at priority level 1. The results of using these options depend on the workload of the application, as well as the load of the system in general.

For more information on the taskset and chrt commands, see their respective man pages. For more information on setting these attributes within an application, rather than when launching the application, see man 2 sched_setaffinity and man 2 sched_setscheduler.

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What is middleware? In plain English, please.

I listened to a webcast from JBoss World today with a group of people. After hearing several speakers announce new middleware products and initiatives (as JBoss is the leading force in open source middleware), one of them turned to me and asked, “Just what is middleware?” When I started to describe transaction servers and database connection pool sharing, she held up a hand and said, “No. I want to know what it is in real world terms, and why it’s a big deal.” » Read more


Tips and tricks: How can I disable device-mapper-multipath in Red Hat Enterprise Linux 5?

In Red Hat Enterprise Linux 5, device-mapper-multipath is installed by default. This is a change from Red Hat Enterprise Linux 4. If a third party multipathing solution is in use, device-mapper-multipath should be disabled to avoid any conflict between multiple multipathing technologies. To disable device-mapper-multipath, turn it off with the following command:

chkconfig multipathd off

In addition, make sure the /etc/sysconfig/mkinitrd/multipath file has the following line:

MULTIPATH=NO

By default, /etc/multipath.conf has all devices blacklisted. If this default configuration has been changed, the change should be reverted. If the devices are not blacklisted, then running the multipath command could cause a conflict with other multipathing software. The /etc/multipath.conf file should contain the following:

# Blacklist all devices by default. Remove this to enable multipathing
# on the default devices.
blacklist {
        devnode "*"
}

These steps will ensure that device-mapper-multipath does not conflict with any other multipathing solution in use.

» Read more


Friday round-up

It’s been a while since we posted a good round-up, and there’s so much we’ve come across lately that we really wanted to tell you about. In no particular order, here’s a list of things that have piqued our interest in the last few weeks:

  • Thomas Chung’s photo essay from SCALE 6X.
  • Here is another SCALE 6X trip report from Fedora Engineering Manager Tom “Spot” Callaway
  • Mary Lou Jepsen’s (the former CTO of the One Laptop per Child project) keynote at the Greener Gadgets conference: How green is the XO?
  • Top 10 Linux distributions for audio
  • Check out Gobby on fedoraproject.org. For those not in the know, Gobby is “a free collaborative editor supporting multiple documents in one session and a multi-user chat. It runs on Microsoft Windows, Mac OS X, Linux, and other Unix-like platforms.”
  • More One Laptop in the news: A comparison of sub-$300 laptops
  • Dave Eggers, winner of a 2008 TED prize, wants 1,000 people to engage with their local public schools through onceuponaschool.org. They need domain hosting, developers, and non-technical people. A perfect opportunity to combine open source’s benefits with education…
  • Love. As in the love of game development. Check out the amazing graphics in this multiplayer first-person shooter game that was created entirely by one person.
  • You’re going to have to pull yourself away from the screen sooner or later. When you’re looking for something to eat this weekend, may we recommend bacon cups? (Because here at Red Hat Magazine? We like bacon.)
  • Neil Gaiman’s giving away books and name-checking Cory Doctorow. Trent Reznor’s up to much of the same with NIN’s new album, Ghosts. Yay for major artists getting on the sharing bandwagon.
  • And speaking of Cory Doctorow, check out this list of 20 science fiction novels that will change your life. Down and Out in the Magic Kingdom is a particular favorite and shouldn’t be missed. But what’s your favorite that didn’t make the cut? For us? Madeline L’Engle’s transformative series about the Wallace family, starting with A Wrinkle in Time.