• Linux,  Work

    Leap second causing ksoftirqd and java to use lots of cpu time

    Today there was a leap second at 23:59:60 UTC. On one of my systems, this caused a high CPU load starting from around 02h00 GMT+2 (which corresponds with the time of the leap second). ksoftirqd and some java (glassfish) process where using lots of CPU time. This system was running Debian Squeeze with kernel 2.6.32-45. The problem is very easy to fix: just run # date -s "`date`" and everything will be fine again. I found this solution on the Linux Kernel Mailing List: http://marc.info/?l=linux-kernel&m=134113389621450&w=2. Apparently a similar problem can happen with Firefox, Thunderbird, Chrome/Chromium, Java, Mysql, Virtualbox and probably other processes. I was a bit suprised that this problem…

  • Linux

    Multi-monitor support with Randr 1.3 and NVidia’s proprietary driver

    I just got a second monitor at home and wanted to configure the two monitors with my NVidia graphics card. You can set up TwinView in the Nvida Settings application, however I did not like that solution: the next time I restarted X, all the settings were lost and the second monitor powered off. Also GNOME did not seem to behave correctly when the monitors went on stand by and I unlocked the desktop. The desktop appeared to be shifted over the monitors. The latter might be a bug of gnome-settings-daemon 3.2 and not Nvidia’s however. However since the NVidia proprietary driver version 330 beta series, it finally supports Randr…

  • Linux

    Creating your own GNOME session based on cairo-dock and Compiz

    Personally I absolutely do not like the gnome-shell in GNOME 3. I actually even hate it: it is slow, messy and cumbersome to use and I have the feeling that developers are not listening to criticism. Obvious and trivial design bugs which are well known, are totally ignored (bug 662738 is an example). For that reason, I went looking for an alternative desktop. KDE is way too bloated for a netbook with 1 GB of RAM, while XFCE is not as polished as a traditional GNOME 2.32 desktop. The best alternative I could find out right now, was to just replace the GNOME Shell by a custom panel or dock…

  • Linux,  Work

    Fixing grub-probe error: Couldn’t find PV, check your device.map.

    Today I was getting this error when installing a new kernel on a server running Debian: /usr/sbin/grub-probe: error: Couldn't find PV pv2. Check your device.map. The error can be reproduce by running the update-grub command. The day before, a new RAID disk was added to this server, so I suspected this could be the cause. The file /boot/grub/device.map contained a reference to the first RAID disk as (hd0) but did not contain a reference to the new RAID disk. I ran # ls -l /dev/disk/by-id/ to find out which SCSI ID referred to sdb (the new RAID disk), and then added the following line to device.map: (hd1) /dev/disk/by-id/scsi-3600304800087c4f015fb4f2e4cc7a8e5 Now installing…

  • Linux,  Work

    Linux performance improvements

    Two years ago I wrote an article presenting some Linux performance improvements. These performance improvements are still valid, but it is time to talk about some new improvements available. As I am using Debian now, I will focus on that distribution, but you should be able to easily implement these things on other distributions too. Some of these improvements are best suited for desktop systems, other for server systems and some are useful for both.

  • Linux,  Work

    DHCPd failover

    Last week, I set up two dhcpd servers in a fail-over configuration. The goal is that when one DHCP server goes down, the other one takes over so that clients don’t lose their network connection. I read different tutorials on the web, such as this one of a fellow blogger and this documentation published by IBM.

  • Linux,  Work

    Server migration to Debian

    Since this afternoon, this server is now running Debian GNU/Linux Squeeze. Just like the previous system, this is a KVM virtual machine running on a HP Proliant DL185G5 host. The host server has always been running Debian. This was my last production system still running Mandriva. I might have forgotten to move over a few things or there might be some breakage somewhere, so let me know if you encounter a problem.

  • Linux

    Why prefer Debian GNU/Linux over another distribution

    Quite some time ago I wrote a blog post explaining why I preferred Mandriva over other distributions. But I have now switched to Debian GNU/Linux, so it is time for an update. I will mostly compare with Mandriva because that is where I come from and what I know the best, although most points are rather universal. So, these are some reasons why I prefer Debian GNU/Linux over other distributions: All officially released Debian GNU/Linux stable versions are supported for a long time. Where most other free distributions are supported for about 1,5 year, this is much longer for Debian stable. For example, security updates for Debian Etch were published…

  • Linux,  Work

    A wise server migration

    Yesterday I migrated two servers at work to a new machine. The old machines were pretty underpowered: a Pentium III 1 Ghz system (with 384 MB RAM if I remember correctly) and a Pentium 4 system. The new machine is a Dell Poweredge R410 with a Xeon E5504 processor, 12 GB RAM and a PERC H700 RAID controller (which is actually a LSI MegaSAS 9260) with 3 750 GB SATA disks in RAID 5. The hardware is pretty nice (although I am not happy at all with the way Dell treats its customers, so I will rather prefer other vendors in the future, but maybe more about that in a…

  • Linux

    Debian on desktop systems

    What I expected to happen some time ago, is finally becoming reality: Debian is now my favourite distribution for desktop systems. First I installed Debian on my new Samsung N210 netbook and I was very pleased with the result. Shortly after that, my father experienced a bug while trying to print in Firefox on Mandriva 2010.1. It would fail to print and there were errors related to ps2ps (if I remember correctly) in the Cups log, hinting at some bug in Ghostscript. Actually it was not the first time this bug hit us, I had seen the same problem some weeks ago. As analysing and having this bug fixed would…