john.parnefjord.se Reflections & findings

The other day I was struck by a strange error in a MySQL 5.0 database. A PHP-page that I've made to upload files suddenly stopped working with the error message:

If you are planning to generate PDF:s programatically in Python you have most likely ran into ReportLab. This is an amazing toolkit to create PDF:s. ReporLab has an addon called renderPM that lets you generate images as well in different formats. When I tried to make a PNG-file I ran into an error with some fonts missing. The code I tried to run was just a simple snippet:

This is the case: the Ubuntu/Debian installation is made with the root folder placed on one disk together with the swap disk. Unfortunately the disk is beginning to become a bit crowded and the amount of freespace is continually diminishing. So, with a new disk plugged in the machine it's time to move the directory /var to the new disk. Assuming that the disk is in place and recognized by the OS, lets get moving:

Create a partition using fdisk on the new disk, in this case /dev/sdb. In the text below I've choose the commands

Updating BIOS and firmware on the server should be done just as the operative system is updated. Earlier most updates were installed using an ordinary floppy, but nowadays most servers are shipped without any floppy drive installed (but some of the firmware countinous to be released as floppy images). A lot of the updates are distributed as packages adapted for different operative systems, which most of the time means Windows, RedHat and Suse as they are officially supported by most vendors. IBM is no exception to this.

Most servers ship with dual network interfaces nowadays in order to have redundant net access. Of course, having two separate cards is preferable, but even if it's a dual NIC installed why not use both ports? A fail-over solution has been the primary concern for me, in other words if one NIC goes down the other NIC should automatically take over. There are quite a lot of terms describing this and some call it bonding other teaming. Whatever it is called this is how I configured fail-over for two NICS on Debian. 

In the testing phase in some projects I want to have maintenance time during some hours each day. Of course I can tell the testpersons that the site will be unavailable during certain hours, and I do, but the human memory too often fails to remember such important pieces of information. Instead of just relying on the human frailty I made some rewriting rules to make it obvious for those who have not been gifted. This is the solution I came up with.

Most Linux distributions are by default shipped with UTF-8 encoded locale nowadays. Unless the user makes an active choice during the installation english locale is the default choice. In Debian Etch it's american english, en_US.UTF-8. For my concern I use swedish as locale, hence I use the locale sv_SE.UTF-8. However, even if the encoding in the system is correct UTF-8-encoded files show up like gibberish in the console when trying to display "exotic" characters. What is needed is another font to display the content.

We run PostgreSQL for some large databases and it works very good. The servers have 32GB RAM each and is connected to a fast SAN, so what should you expect. But there are some important things that need to be considered in order to maximize the performance.

IBM ships most tools packaged just for Suse and RedHat, quite annoying when running Debian or Ubuntu isn't it? Anyway I've tried earlier to install Director on Debian, but I gave up after a while. It was an overweighty system and I just wanted to be able to monitor the server, especially the raid. After some searching I found the arcconf-tool via Adaptecs site. But after some more searching I found the IBM version.

I started using Python a while ago and one of the things I need to do is to be able to connect to Microsoft SQL server from Linux servers. I was a bit surpised that I could only find some relics from projects not alive any more or the commercial MxODBC from eGenix. Then I ran into pymssql and decided to give a try. It worked almost at once on my virtualized Ubuntu Gutsy test box.

First I installed the prerequisites: freetds and the python headers: