Planning Servers for Failure

Sometimes computers fail. If you run enough computers then you encounter failures regularly. If the computers are important then you need to plan for the failure.

An ideal situation is to have redundant servers. Misconfigured clusters can cause more downtime than they can prevent and it requires more expensive hardware to properly implement a cluster […]

Some Tips for Shell Code that Won’t Destroy Your OS

When writing a shell script you need to take some care to ensure that it won’t run amok. Extra care is needed for shell scripts that run as root, firstly because of the obvious potential for random destruction, and secondly because of the potential for interaction between accounts that can cause problems.

One possible first […]

First Dead Disk of Summer

Last night I was in the middle of checking my email when I found that clicking on a URL link wouldn’t work. It turned out that my web browser had become unavailable due to a read error on the partition for my root filesystem (the usual IDE uncorrectable error thing). My main machine is a […]

Debian SSH and SE Linux

I have just filed Debian bug report #556644 against the version of openssh-server in Debian/Unstable (Squeeze). It has a patch that moves the code to set the SE Linux context for the child process before calling chroot. Without this a chroot environment on a SE Linux system can only work correctly if /proc and /selinux […]

Backing up MySQL

I run a number of MySQL databases, the number of mysqld installations that I run is something like 8, but I may have forgotten some. With the number of servers that I run on a “do nothing except when it breaks” basis it’s difficult to remember the details. The number of actual databases that I […]

What to do When You Break a Server

Everyone who does any significant amount of sysadmin work will break a server. Most people who have any significant experience will have broken several. Anyone who has never broken one should be treated with suspicion by other members of the sysadmin team, they probably haven’t learned the caution that most of us learn from stuffing […]

Links November 2009

Credit Writedowns has a populist interpretation of the latest Boom-Bust cycle [1]. It’s an interesting analysis of the way the US economy is working.

Bono writes for the NY Times about Rebranding America [2]. He praises Barack Obama suggesting a different reason to believe that the peace prize is deserved and describes what he believes […]

I’m an Aspie

I’ve recently been diagnosed with Asperger Syndrome (AS) [1]. Among other things this means that I am genetically predisposed to have an interest in solving technical problems and give lectures about how I solved them, but that I tend not to be a “people-person”.

AS is generally regarded as an Autism Spectrum Disorder (ASD), but […]