Articles

Manipulating SCSI devices in the kernel

You've added a scsi disk on a controller and you don't want to restart linux to scan the scsi bus ? Tell the kernel directly that a new scsi device was added .

The previous method was to use the echo command talking to /proc/scsi/scsi : For example , we've added a scsi disk on the first scsi controller (0), on the first channel (0), with a scsi id 4 (4) and on LUN 0 (0) : echo "scsi add-single-device 0 0 4 0" > /proc/scsi/scsi

Now (better and updated solution) : echo "- - -" > /sys/class/scsi_host/host0/scan

Check with cat /proc/scsi/scsi that you're able to see the device and use the disk without having to reboot ....


Java apps and AIGLX (compiz) gray screen problem

I had recently to test the newer Lotus Notes 8 beta 2 apps on my CentOS 5 laptop. The java installer starts but displays nothing more than a gray screen. This is a known behaviour with java apps (problems occurs also with the xenserver-client package). Solution is to add the following line in your \~/.bash_profile : export AWT_TOOLKIT=MToolkit

Log again and java apps will display correctly


AdobeReader 7.0.9 on CentOS 5 expr problem

I like Evince to read pdf documents on CentOS 5 , but i wanted also to use the Adobe Reader to do it ... but each time i wanted to launch it, i had a "expr: syntax error" error while launching the /usr/bin/acroread script. Solution is to edit this file and remove a check : check_gtk_ver_and_set_lib_path "\$MIN_GTK_VERSION" . After that, it works ok ...


LVM on top of DRBD devices

I wanted to use lvm on top of drbd devices so that i can add more disks as drbd resources and integrate them in a vg. pvcreate /dev/drbd0 will work ok, but if you use vgcreate yourvol /dev/drbd0 it will complaint about duplicate pv. So how to use drbd devices with LVM. Solution seems to use a filter option in /etc/lvm/lvm.conf to ignore real devices and use only drbd devices . More informations on the drbd mailing list archive


some extra rpms for CentOS 5

I needed several rpms i was not able to find in any other third-party repo. This include pptpconfig (a pptp client i need to support some customers relying on this poor protocol), brasero (nice gtk burning software), audacity, etc ....

So i've just (re)built them on CentOS 5 . If you're interested, you can grab them with yum by following instructions on http://rpms.arrfab.net . Please note that i've built such packages only for i386 (i've no x86_64 available at this time) ...


CentOS 5 minimal install

As you've probably noted, the minimal install checkbox is missing from anaconda on CentOS 5. But if you unselect every group, choose 'customize now' and then unselect everything (including Base), you'll end up with a 594mb minimal installation. Then you can customize yourself what you want to remove (like the Deployment guide) and what to add (with yum).


Compiz with Nvidia drivers on CentOS 5

I've just installed my main workstation at home with CentOS 5 ... this one has a nvidia video card (GeForce 6600) and i installed official nvidia drivers ... but after that i was not able to enable desktop-effects (compiz). You need to add something in your /etc/xorg.conf for compiz to work with nvidia drivers ... here they are (verify that they exist in your existing xorg.conf or add them) :

Section "Module"
Load "glx"
Load "extmod"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "nvidia"
Option "AddARGBGLXVisuals" "True"
Option "DisableGLXRootClipping" "True"
EndSection

Section "DRI"
Group 0
Mode 0666
EndSection


A friday afternoon test

I had foolish idea this friday afternoon. I was at the office and i tested an upgrade from CentOS 4.4 i386 (32 bits) running on a IBM HS20 Blade server to CentOS 5.0 X86_64 ! Some will say (and i agree) that such thing is a silly thing to do , but the sun was shining and i had to reinstall the blade anyway ... But strangely, it worked ! I upgraded with Anaconda (through an NFS install). The only problem i had was related to udev and linuxwacom. I had to remove the old udev package (that was left behind) and verify the newer one ... but after that everything was running perfectly ! Of course that's something i'll never do on production servers ... :o)



IBM Lotus Notes for linux sucks

It's been a while that i've installed the Lotus Notes client for Linux on my laptop ... but because i've reinstalled my laptop from CentOS 4.4 to CentOS 5 , i needed to setup this crappy client once again ... 'crappy client ?' yes . First of all, IBM decided to release such tool only with its own installer (that is java based of course) ... so no RPM available (hmmm, that should have been too easy for stupid end users i guess ...) . The problem with such installer is that it doesn't even verify if you have dependencies ... it only installs a java-based workplace client (by default in /opt) but if you do it as root, it will try to setup the Notes plugin for the root account only ... (hehehe the Lotus notes client for Linux is not multi-users aware yet ...) . So recommandation is to create a /opt/IBM directory and let the user modify this directory ... You launch so the installation as a simple user but when it finishes you think you can now configure the client .... no !

Because no dependencies were checked you have to use ldd and strace to find what it is missing .. (in my case , using ...