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About linux filesystems
edited by on July 28th 2007, at 23:02


Has no journalling, so preferrably only used for CF and USB sticks, or for very small file systems where journalling makes things worse than better.

No indexing, so don't use for many files.

Preferred choice for external storage, because virtually all systems can read ext2/ext3 (including Windows with proper software).

Has journalling. Is perfect for all-round (server) systems, in particular root file systems and such. If there are many small files, and many files in one directory, this one is not the preferred choice because there's no specific indexing method (or none that I know of).

Has full resize support, so can be used for LVMs.

Is robust: has proven its worth.

Disaster recove  ...
 
Client-only MythTV
edited by on July 24th 2007, at 23:38
In light of my media guide (which is still under heavy development), I did a bit of experimenting with MythTV.
The result of my experiment is pretty nifty: I now have the ability to watch TV on my laptop (without a TV tuner), as long as I have a connection to my media PC (where the tuner is). Want to know more? Read on then...

As you know (or perhaps not yet), MythTV consists of two parts: a backend server (which does all the work: managing records, accessing hardware and so on), and a frontend client (basically controls the backend server, look up recordings, watch actual TV, etc.).
These two parts communicates with each other using the IP stack. While (according to the Gentoo ebuild maint  ...
 
The Simple Guide to a Media PC
edited by on July 13th 2007, at 18:10
Because of my move, I had need of a media PC system, which allowed me to watch TV, record from TV, watch DVDs, listen to music and more. Buying a pc with Windows Media Center was not an option: linux has very wonderful applications and utilities to build such a sytem. For hardware, I had an old pc which I used as a server, but because of the wonderful capabilities of VMware, I decided to convert the machine to a so-called Media PC.

To contribute my efforts to the community, I decided to create some sort of a guide. It is not a real how-to, but rather the steps I took to get things running, along with descriptions and solutions to caveats and problems I encountered.
The guide can be found i  ...
 
Sprung a leak...
edited by on July 2nd 2007, at 21:02
Well, isn't this great... Thought I had a quiet weekend (well, relatively quiet, read the next post), with a bit of gaming and such. But apparently, my oh-so-wonderful water-cooled video card thought otherwise.

Twas Friday afternoon: I booted up my pc. Although it was a bit more silent than usually, I discarded it as being the bit cold weather of these days.
Thought it would be neat to do a bit of retro-gaming, and fired up the old Half-Life 1...

About two minutes in the game, alarms and whistles and popups went off, and as the message your card is too hot appeared on the screen, I distinctively shouted out: WTF!
I quickly cranked up the ATI console, and saw an astonashing 113 degrees C !   ...
 
The importance of battery backup in a RAID controller
edited by on June 28th 2007, at 15:34
Did a test on two DL380 G5 controllers to check out the difference between having a battery or not on a P400 SAS RAID controller. The results are remarkable, to say the least.

Both machines are fairly identical when looking at disk configuration: both have a P400 SAS controller with an equal amount of storage, but srv1 has 512MB with battery, srv2 has 256MB without battery.

I ran a dd test of a file, and this is the output:

srv1:~# dd if=/dev/zero of=./dump.dump bs=1k count=81920008192000+0 records in8192000+0 records out8388608000 bytes (8.4 GB) copied, 48.282 seconds, 174 MB/s

srv2:~# dd if=/dev/zero of=./dump.dump bs=1k count=51200005120000+0 records in5120000+0 recor  ...
 
[Exchange] mailbox sharing and delegation
edited by on June 26th 2007, at 09:23
 
[Mac] Memory stick not empty after deleting files
edited by on June 24th 2007, at 20:24

A friend of mine had this problem with her camera storage thingy. If you're a MacOSX user, you might want to read up on the symptoms and solution on her blog.
Extra thanks go to Heidi for this.

 
Finding Windows uptime
edited by on June 11th 2007, at 11:37
In linux, punching in uptime provides you with how long the system was up without a reboot. But how to do this in Windows? There is no real indication to be found anywhere. Here's how.

The uptime can be found using the command prompt.

Do a start -> Run, punch in cmd and hit Enter (like you normally would).
Type in the command:

net statistics server

(and hit Enter).
Find the line that starts with Statistics since...: it will tell the time the server was up from.

Note that you could shorten the commands like so:

net stats srv

The above has been tested with: Windows 2000 (all versions), Windows XP (all versions), and Windows 2003 (all versions). It will probably work on Vista as well.
  ...
 
OpenVPN on Vista: issues
edited by on May 21st 2007, at 17:59

Running OpenVPN on Vista, works, but requires some workarounds.
Current list of issues:

  • connection gets established, but route addition fails with route addition failed usingCreateIpForwardEntry

Read further for the solutions...

connection gets established, but route addition fails with route addition failed usingCreateIpForwardEntry

This problem always occurs on a Vista. What happens is that while the connection does get established, the routes are not being added properly, because of an API change in Vista.
To circumvent the issue, add this line to your OpenVPN config file:

route-method exe

This way, the route addition is called directly using the commandline utility.

 
Exchange 2000/2003: change in-/outgoing SMTP port
edited by on May 17th 2007, at 15:24
Because of (Belgian) providers limiting SMTP (port 25) traffic to their own servers, makes it necessary for us (as an 3rd party ISP) to allow our customers to use our own mailserver for all outgoing mail. To circumvent this limitation, we've configured the mailserver to listen on port 26 as well.

For our customers with only a few mail clients (so no local mailserver), this is usually not a problem. A quick change of the SMTP port, solves their issues. For people that have a catch-all mailbox (and a local mailserver), the mailserver itself usually allows the change.

Of course, some of our clients have Exchange servers, and there, the change was not that obvious.
After a bit of a search, we'  ...
 
Windows XP: Illegal System DLL Relocation
edited by on May 14th 2007, at 21:10

It's a bit of an old post, but ran into this problem more than once.
If you get the message:

Quote
The system DLL user32.dll was relocated in memory. The application will not run properly. The relocation occurred because the DLL C:\Windows\System32\Hhctrl.ocx occupied an address range reserved for Windows system DLLs. The vendor supplying the DLL should be contacted for a new DLL.

A hot-fix can be downloaded at: http://support.microsoft.com/default.aspx/kb/935448.

 
HP Proliant ML350 G5 woes: part 3
edited by on May 7th 2007, at 11:09
It would've been too easy if the solution (read my previous post about this topic), would've just worked. With the source of the HP OpenIPMI package available (it seems to be included in the download), I thought it would be snap to get it compiled for our Etch kernel. I was wrong...

Downloading the .deb for sarge doesn't work on Etch right away because of a kernel version difference. Moreover, while the source of the OpenIPMI driver has been included, it does fit neatly into the kernel source, but the compiler bombs out with this:

  CC [M]  drivers/char/ipmi/ipmi_msghandler.odrivers/char/ipmi/ipmi_msghandler.c: In function 'ipmi_smi_watcher_register':drivers/char/  ...
 
HP Proliant ML350 G5 woes: part 2
edited by on May 4th 2007, at 15:05
After a call to HP, there seems to be a solution present.
Apparently it's a known issue on these boxes, when one is using the open source IPMI, instead of the HP OpenIPMI.

The resolution was to install HP OpenIPMI. The full description is below:

Quote
DESCRIPTION
On an HP ProLiant ML350 G5 server configured with a single processor, if
the HP System Health Application and Insight Management Agents for Linux
are installed without the HP OpenIPMI (hp-OpenIPMI) device driver
loaded, a console message is displayed indicating that there is a
problem with the system fan and that the server will shut down in 60
seconds. After 60 seconds has passed, the server reboots. When this
occurs, the followi  ...
 
HP Proliant ML350 G5 woes
edited by on May 3rd 2007, at 16:01
Some time ago, Debian has finally been adopted officially by HP as a supported Operating System. They even have released packages for Sarge for it.
Of course, in the meantime, Etch is the new stable of Debian, thus, I had to revert back to the old tweaking ways, described at http://debian.catsanddogs.com/. On the various DL380 G5's I've worked with, this went very smoothly, and it runs perfectly. On the ML350 G5, it's something else...

The machine is a new ML350 G5, with a dual-core Xeon 5120. The system runs Etch AMD64 (stable), and everything seems to be in order. Installation of the agents went flawlessly either (with a bit of script tweaking to make up for the version difference).

The   ...
 
Tuning in on live streams (audio)
edited by on April 29th 2007, at 19:46
In this article, you'll find some pointers on listening/watching to live streams with certain software applications.

MPlayer is a very good application when it comes to live streams. It supports a whole deal of protocols, including those of windows (mms://).
The only "drawback" is that MPlayer by default sets its cache to 8MB. For video over LAN, this is not really an issue, but when listening to a low bitrate audio stream on the internet, it takes a long time to fill up that cache.

The easiest way to listen to a live stream:

mplayer -cache size-in-KB "stream-url (e.g. http://)"

Be sure to set cache size to something more sane:

For low bitrate audio streams: 64 or   ...
 
Securely clearing a harddisk
edited by on April 29th 2007, at 19:40
There are two things you need:

A bootable linux LiveCD, preferrably Knoppix, but any other distro with all basic linux tools will do.

Some knowledge on how to use commandline based programs (and perhaps some knowledge with linux in general).

First, make sure to boot with your LiveCD. You won't need to boot entirely into the graphical interface.
For Knoppix, the boot: commandline would be something like:

boot: knoppix 2 lang=your-keyboard-layout vga=normal

You can leave out the vga=normal to use framebuffer instead of plain text mode. Replace your-keyboard-layout (keyboard layout) with your country code: for Belgium (azerty), this would be lang=be; for standard US (qwerty), use lang=  ...
 
A thing or two about kernel frequency
edited by on April 28th 2007, at 00:46
In short: the kernel frequency is the number of interrupts (IRQs) handled by the kernel per second. Like most applications of frequency, it's also expressed at Hz (hertz).

A more sound explanation of interrupts can be found here, but it basically boils down to this: an interrupt is generated each time an event on a piece of hardware (in the most elementary way; this includes your keyboard for instance), and requires the necessary CPU time to handle that event. This is called interrupt handling.

Now, because the kernel directly interacts with all the hardware around, it's vital to have it handle interrupts; actually, it's the kernel that handles interrupts, by using the CPU.

Very simple: t  ...
 
Input trouble with PuTTY SSH on Debian
edited by on April 28th 2007, at 00:37
If you happen to have keyboard trouble when you SSH with PuTTY to a Debian system, you might want to read on.
With trouble, I mean one or more of the following symptoms:

Numeric keypad not working, even with numlock enabled/disabled

Home/End keys not working as they should

Function keys not working as they should

Other weirdness concerning keyboard...

We've figured out a possible solution to the problem. It has been tested (and used) extensively by my and a collegue, and have found it working perfectly on Debian Woody and Debian Sarge.
It may be possible that these settings also work on other distros having similar problems. If it does, please let us know so we can add it to the article  ...
 
Setting affinity on dual-core CPUs with ROPE
edited by on April 28th 2007, at 00:32
The bliss of dual core can quickly turn to a curse when you're running applications that weren't build to handle multiple CPU's.
Although one could set affinity with windows task manager, the application often goes down before one could alt-tab to set it, or sometimes, the application doesn't even start at all.

A quick search on the web has brought me on a forum thread, where they were talking about RunOnProcessorExplicit, or in short: ROPE.
ROPE is a very simple tool, that allows you to set affinity directly at the start of an application. This circumvents the need of using windows task manager and moreover, allows you to change shortcuts accordingly, so you won't have to remember to set a  ...
 
Sync your website with rsync
edited by on April 28th 2007, at 00:18
If you are blessed with ssh access to your webhosting, then a world of goodies opens up. One of these is rsync. When installed on your webhosting (which usually is), you can use this instead of ftp to maintain your website.

Rsync is mainly used for syncing two file structures (directories and subdirectories) together. It works by comparing the two structures and check out each directory and files on modified date and time, but also content of the file (using hashes).
While mostly used for backup, this thingy is very handy when maintaining a website. Rather than figuring out which files need to be copied, rsync does it all for you with a single command.

rsync -e ssh -rltDv <local website  ...
 
showing posts tagged with 'computer'
 
 
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