Tales From The Geek Side

I recently attempted to install Debian 5 using the latest net install iso image using Virtual Box (the commercial/non-open source version). The installs kept failing. I finally tracked it down to not having enough RAM available. 256MB was not enough but bumping the virtual machine setting to 512MB did the trick.

(This tip provided by John Ghidiu)
Sometimes evolution will be out of sync with the exchange server. As I write this it’s a known problem. The workaround is to force evolution to shutdown and then force it to rebuild the local folder cache.

It seems that Evolution getting out of sync with Exchange is an old, old bug. If you run:

evolution –force-shutdown
rm -rf ~/.evolution/exchange//folders.db (this is the cache, I think)

and then start Evolution again, things work again.

My file server appeared to have some filesystem issues. I wanted to check and repair the filesystem but I couldn’t find my system rescue CD on a USB stick. I considered rebooting the machine 30 times to force a check but that didn’t seem like a fun way to spend my time. The filesystem is the root filesystem and it is xfs which meant that I couldn’t use `tune2fs` to set the property to force a fsck.

Today I learned of a very easy way to force a file system check. That is to create a file /forcefsck. The startup scripts in the initial ramdisk will check the filesystem and remove the file.

It seems that every time I setup a diskless Linux machine I run into the same problem — nfs mounts hang. I’m not talking about the root filesystem. That mounts fine but other mount points result in mount hanging. Then I track the problem down to rpc.statd and portmap hanging. I also end up coming back to my blog to search for the answer to this problem and get frustrated when I can’t find the answer that to a problem that I’ve solved over and over. So, once and for all, I present the solution to the problem that I know I’ll encounter again.

The problem is that the localhost interface is not defined in /etc/network/interfaces and this causes problems (I do not know why) with the nfs/rpc tools. When I setup diskless machines I use debootstrap to create a root file system. Debootstrap correctly leaves a few things unconfigured. The localhost interface is one of them. And so I say to my future self, “self, just add this to /etc/network/interfaces and all will be well. And calm down this isn’t a big deal!” :

I’ve had an excellent setup using MythTV and a VIA M10000 based system. The M10000 is the frontend which has a 1Ghz VIA chip and onboard hardware support for mpeg2 decoding. When watching TV shows that I recorded using an analog tuner card the system showed about 10% CPU utilization! It was perfect…until digital TV arrived.

Actually the M10000 is fine for digital television if the resolution is in the standard def ranges. 720p content and 1080i content it can not handle in real time. This is because the hardware MPEG decoding is limited to a maximum resolution which the HDTV broadcasts exceed. The onboard CPU isn’t nearly powerful enough to decode the content in real time.

I decided to move my desktop system, a 2Ghz Pentium-M based SD11G5 from Shuttle, downstairs to be my new myth frontend. At the same time I decided to get rid of the Myth frontend software and instead use XBMC. I did some tests and it seemed like it would work perfectly.

Once I got everything setup I found that things did not work perfectly. My testing was with 1080i broadcasts which I assumed would be more taxing on the system than 720p broadcasts. I was wrong. The system can handle 1080i just fine but it can not keep up with 720p. This must be due to the frame rate.

I now have a dual core atom system with an NVIDIA video card. Using XBMC with VDPAU support I should be able to decode anything I throw at the system. I’ve built the system but I haven’t setup XBMC for it yet. I’ll report out when I get that fully functioning.

Sometimes you need to update packages on a Debian based system but you don’t want to updated all of them. For example there are security updates available right now for a system I manage. One of those updates is the linux kernel. I’m not ready to upgrade the kernel because it is a remote machine that many people depend on. To do a kernel upgrade I need to schedule downtime and prepare for the case when the system doesn’t reboot after the upgrade.

With Debian based systems you can handle this by placing packages on hold. Packages that are on hold are not updated. If you use aptitude this is as easy as:

If you use apt-get you can accomplish the same thing with:

When you are ready to update the package you can take it off of hold with (for aptitude):

And for apt-get/dpkg it is accomplished by:

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0.8.3 is my final release.

I am no longer maintaining tcl-dox. It started as a fun experiment but I’ve lost interest. Tcl-dox is highly error prone and difficult to maintain because it is based on regular expressions. I may work on
a new version of tcl-dox that uses libtcl and the Tcl_ParseCommand function to do far more robust and reliable translations. …But time is scarce and I can’t promise that I’ll ever get around to that.

If you wish to take over tcl-dox please let me know. I’ll post about it here so any existing tcl-dox users can easily find the new home.

This release fixes a couple of very minor issues. I can’t promise that this release is any better than the others.

All too frequently I need to convert text files with DOS line endings to UNIX line endings.  It’s easy to do using tr but I can never remember the syntax.   The following strips the carriage returns (\r) and end-of-file characters (^z) from the file:

$ tr -d '\15\32' < dosfile.txt > unixfile.txt

I’m a somewhat casual user and administrator of the Mantis bug tracker.  Mantis is an issue tracking system written in PHP that includes a SOAP interface.  You don’t have to use the SOAP interface as it comes with a suitable HTML user interface.

Lately I’ve been loaded with more responsibility at work.   To keep track of the projects that I’m working and what other people are helping me with I’ve started using Mantis much more heavily.  One thing that started to frustrate me is that I wouldn’t know when people submitted new issues unless they were assigned to me.

There’s a GUI for managing email notifications that you can use at the global level or override on a per-project basis.  I enabled email notifications for new issues for “developers, managers, and administrators.”  Then I created a dummy issue as a test.  I was shocked to see that Mantis sent emails to ALL developers, managers, and administrators in my entire company!  I expected these messages to be sent to just the developers, managers, and administrators assigned to the project.

After much googling I finally found the answer.  If a project is public it will send those emails to everyone because everyone has visibility into those issues.  I had set all projects to public because I leave things open by default.  I prefer to promote communication in my company.  This also explains the (at the time) perplexing user interface for managing a project that listed everyone as a member of the project but only those that were truly project members had “remove” buttons.

So if you want to send out notifications of new issues to all members of a project make sure your project is private.

I recently learned about XBMC, a very nice cross platform media center application.  After encoding all of my music in mp3 format I tried to use the Myth Music plugin.  It works but I found it awkward and difficult to use.  XBMC looks much nicer and can work as a MythTV frontend!

My current frontend is a mini-itx system that uses a VIA chip.  It’s the M10000 board.  It’s been great.  The board is not powerful enough to decode, in real time, any 720p or 1080i recordings that I make (I have an analog tuner card and a digital tuner card).  With the upcoming switch to digital TV broadcasts my options are to transcode everything or to upgrade my frontend.  Transcoding doesn’t appeal to me since it takes a very long time to do.  Besides I couldn’t watch anything as it is recorded.  I sometimes start watching a show 15 minutes after it has started.

I’ve been using a Shuttle SD11G5 for quite a while as my desktop system.  It’s a 2 Ghz Pentium M system with an Intel 915 graphics integrated graphics card.  My hope was that this machine would be powerful enough to decode over-the-air broadcast HD.  I’m happy to report that it does — mostly.

Using the XBMC live CD I booted XBMC.  The default resolution was 1024×768.  At that resolution I saw no significant frame drops on 720p or 1080i recordings.  When I bumped the resolution to 1280×1024, the native resolution of my monitor, I saw hundreds of dropped frames.  I also tried 640×480.  Not surprisingly the system could keep up just fine at 640×480.  I’m going to run XBMC at 640×480 (probably) since I have a standard definition TV (a 27 inch CRT).

When I eventually buy a new TV I’ll upgrade the frontend system too.  From what I’ve read a system with a Core2 Duo at 3 Ghz is fast enough to decode even the toughest 1080p videos (H.264 format) in real time completely in software.  An Intel X4500HD graphics chip should be sufficient to handle the OpenGL work that XBMC throws at it.  Until I buy a new TV I’m hoping to get away with not buying any new hardware!