Bashton Blog » centos

Running an Ubuntu Hardy Xen domU under a CentOS dom0

admin — Tue, 23 Sep 2008 08:10:43 +0000

As pretty much always with Linux there’s more than one way to do this, but here’s how I got a nicely working para-virtualized Ubuntu Hardy domU running under a CentOS 5.2 dom0:

Install hardy under an HVM using the standard ISO
Boot into your new hardy install and run sudo apt-get install linux-image-xen (make sure you have universe enabled)
Add appropriate settings to your /boot/grub/menu.lst – here’s what I added:

title Ubuntu 8.04.1, kernel 2.6.24-19-xen root (hd0,0) kernel /vmlinuz-2.6.24-19-xen root=/dev/mapper/dsk-root ro initrd /initrd.img-2.6.24-19-xen

Add a console on xvc0: sed -e 's/tty1/xvc0/' /etc/event.d/tty1 | sudo tee /etc/event.d/xvc0
Power off your Ubuntu VM
On your CentOS dom0, alter the Xen VM configuration file to boot using pygrub, very basic example below:

bootloader = '/usr/bin/pygrub' memory = 1024 name = "ubuntu-test" vif = [ '' ] disk = [ 'phy:/dev/san1/ubuntu-test,xvda1,w']

Restart your Hardy VM and enjoy massively improved performance

~~One thing missing from the para-virtualized VM is VNC support – you have to use the console via the ‘xm console’ command.~~

The procedure should be similar for Citrix XenServer, although it will involve some messing with the xe vm-param-set command rather than editing the config file. When I have a chance I’ll document this too.

Update, 30/9/08:

To enable a VNC console, do the following as well as the above:

Add the framebuffer drivers into the initramfs

echo "fbcon" | sudo tee -a /etc/initramfs-tools/modules echo "vga16fb" | sudo tee -a /etc/initramfs-tools/modules sudo sed -ie 's/^blacklist vga16fb$/#&/' /etc/modprobe.d/blacklist-framebuffer

Re-generate the initramfs

sudo update-initramfs -u -k all

Alter your grub menu.lst to include the boot options console=tty1 vga=normal (best done via the defoptions line, I tend to remove quiet and splash from here too)

Reboot, and you can now use a VNC console as well as the Xen xm console command.

Fix for Perl slowness on Red Hat/CentOS 5

sam — Mon, 08 Sep 2008 07:57:31 +0000

Some of you may have heard about the kerfuffle surrounding poor Perl performance on Red Hat 5/CentOS 5 – it got a bit of attention on reddit/digg. Red Hat had been issuing hot fixes to people who complained, but now Karanbir Singh has created an updated Perl package.

This issue should be fixed in RHEL/CentOS 5.3, but until then, if you’re experiencing slowness I’d advise installing this – after appropriate testing on staging/UAT servers of course.

Django 1.0 Released

sam — Thu, 04 Sep 2008 08:49:02 +0000

The final version of Django 1.0 has been released. Debian packages are available from the unstable repository and these should install cleanly on Ubuntu too.

As I noted previously with the Alpha releases, an RPM for RHEL5/Centos can be built by doing:

python setup.py bdist_rpm

Note you’ll need an updated MySQL-python library installed, which can be found below.

MySQL-python-1.2.2-1.x86_64.rpm

If you’re not using a 64bit server, you can download this source RPM and rebuild via rpmbuild –rebuild:

MySQL-python-1.2.2-1.src.rpm

Linux Server Distribution Comparison

sam — Mon, 18 Aug 2008 08:51:18 +0000

I’ve just put up an long-ish article I’ve written comparing five different server distributions. I fully realise that by doing so I’m opening myself up to hundreds of flames from outraged fans of , all complaining that I’ve treated their pet distro unfairly.

Given that I’ll probably be accused of bias anyway, I better declare mine: the server that is serving you this page runs Ubuntu, as does the one running the main Bashton site. Many of our internal-facing servers run CentOS. My desktop runs Ubuntu, and my laptop runs Debian. Other staff have their own bias of course (particularly those who are Debian developers..), but as it was just me writing the article I don’t see that as relevant.

Please make your comments here and hopefully we can start some form of a useful debate, rather than the ‘distro X is the best’ discussions these things usually descend into.

Python 2.5 RPMs for RHEL 5 / Centos 5

sam — Fri, 08 Aug 2008 13:08:28 +0000

Red Hat Enterprise 5 ships with Python 2.4. As it uses this for the majority if its inbuilt scripts, it’s probably not such a good idea to just change it.

With this in mind, I built the following Python 2.5 RPMs, which create the python executable as /usr/bin/python25. This means that where necessary, you can use Python 2.5, but the system scripts will continue to use 2.4. If you do want to use Python 2.5 by default, by all means make /usr/bin/python a symlink to this – but don’t complain to me if ‘bad things’ happen.

64-bit RPMs:

python25-2.5.1-bashton1.x86_64.rpm
python25-devel-2.5.1-bashton1.x86_64.rpm
python25-libs-2.5.1-bashton1.x86_64.rpm
python25-test-2.5.1-bashton1.x86_64.rpm
python25-tools-2.5.1-bashton1.x86_64.rpm

Source RPM:

python25-2.5.1-bashton1.src.rpm

Django 1.0-alpha RPMs for Centos/RHEL 5

sam — Thu, 31 Jul 2008 12:58:42 +0000

We’ve been using Django a lot for some internal projects, and for various reasons we’re using CentOS 5 on the servers running them.

One nice feature of the Python build system I didn’t know about until today is the ability to make RPMs using the setup.py script. To build yourself some Django RPMs, just run:

python setup.py bdist_rpm

Unfortunately, this feature seems a bit hit and miss. Django needs a newer version of MySQL-python than ships with EL5, but unfortunately the bdist_rpm for this doesn’t work.

As such, here’s a link to an updated MySQL-python RPM I’ve built:

MySQL-python-1.2.2-1.x86_64.rpm

If you’re not using a 64bit server, you can download this source RPM and rebuild via rpmbuild –rebuild:

MySQL-python-1.2.2-1.src.rpm