Tag Archives: xen

Why Are There No Good Automated Deployment Tools for Xen on Enterprise Linux?

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Currently, when I create a new Xen DomU, I have to create a new logical volume, edit a configuration template, install the OS, and finally modify the configuration file to its final post-install parameters. This is a time-consuming process that should be avoided if at all possible, yet I have not been able to find tools to do so.

I came across xen-tools, but its mainly for Debian based systems. It does have some tools to assist in deploying rpm based systems, but they appear to be clunky. The required rinse tool basically downloads packages twice to do the install. Why?

There is also the Red Hat provided Virtual Machine Manager which is GUI based. I like to stick to command line, but that’s OK since they have a tool called virt-install that will either prompt you for information or will accept arguments to configure the new DomU. The issue here is that virt-install creates the sxp file in /var/lib/xend/domains/(hex number)/ making it impossible to restart the machine after it has been started, as well as place a copy in the /etc/xen/auto folder for automatic startup at boot. However, there is a tool to parse the sxp formatted configuration file, back to the normal format… but its an extra step. Why can’t it just use the simple configuration file format from the start?

All I want is a simple tool that I can throw a few arguments at such as hostname and ip addreess to pass to kickstart, something I can have create the LVM partitions for me, and something that will properly output the configuration file to /etc/xen. Why is this so hard and why has this not been done yet?

Rebuiding My Virtual Empire

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I’ve been using virtualized systems for years now and finally began using Xen. Xen is similar to a bare-metal hypervisor like VMWare ESX but instead of using a proprietary host OS, Xen uses Linux. Most of the common Linux distros like Debian/Ubuntu, RHEL/Fedore/CentOS, etc provide support for Xen out of the box. I’m used to using Linux and have used it for years, so it just made sense.

Previously I had used VMWare Workstation for creating test servers, etc., but that required a full host operating system. For a while, I had used Windows, then I was using Linux, but it was still clunky. I had to manually start machines after reboot and if I upgraded the kernel on the host, I had to re-run some perl script to configure VMWare. After a while, I realized it was time to let go and do things the smart way, the Xen way. However, I do still use Parallels Desktop on my Mac just to have something available when I travel.

I have a custom server in my basement that I built a few years back and have modified over time. It has a 2TB RAID 5 array that I use for my network storage. It also has a dual-core AMD processor that I might swap out for a quad-core Phenom early next year. Just before rebuilding it as a Xen box, I upgraded the RAM to the maximum 8GB. Oh, and I added a 640GB drive to store my Xen machines.

I got the Xen Dom0 built the other week and have it running just enough to basically boot and allow me SSH access. This was really just a matter of doing a base install plus the Xen kernel and booting to the Xen kernel post-install. I kept the services to a minimum for security purposes and will run what’s needed off one of the DomU machines. Before I rebuilt this box with Xen, the host OS also doubled as the file and print server. This will be moved over to the first Xen DomU I create.

CentOS 5.2 comes with Xen 3.0 and unfortunately, none of the default repos have Xen built other than 3.0. Xen 3.0 is fairly outdated and I was looking to update to a more recent version to take advantage of the new features. The only options for updating were to upgrade/install from source or to use the wonderful Gitco repo that has a few Xen versions built for EL5 based operating systems.

I’m now the proud owner of a Xen box! I’ve learned quite a bit so far and have gotten my first DomU created. I’ll detail that more in a later post. I’m also looking at setting up Puppet to deploy and manage my machines. That’ll probably be the second DomU that I create.