BMW is using the Xen para virtualisation tool in SuSE Linux Enterprise Server to run test and development production systems. The company has deployed Xen to replace its ageing PA-Risc, Sun Sparc and IBM Power 4/5 Unix server hardware with industry-standard PC servers.
The car maker worked with Novell to replace 1,400 Unix servers with Linux systems. It chose Xen over VMware because native products where the virtualisation is supported within the operating system are easier to maintain, according to Andreas Poeschel, IT specialist at BMW Group.
Novell takes care of any support issues and provides hardware drivers. Additionally, when Novell releases a new service pack, BMW does not have to wait for a third-party virtualisation product to support the service pack, since Xen will include support as standard.
BMW has chosen not to run its database servers on Xen, because the servers are restricted by physical I/O bandwidth, which means their performance is not improved on a virtual machine. Instead, Xen is used to run applications.
BMW uses predominantly open source command line tools to manage the 600 virtual servers it runs on Xen. "Our admin staff prefer scripts [to manage virtual machines]," said Poeschel. "The GUI-based management tools provided by VMware are not essential. If open source software is suitable, we will use it." As such, Linux administrators use familiar command line tools and the bash scripting language to operate the Xen virtualisation environment.
He said it uses easy-to-administer products to manage Xen. "If we used a single management tool it would be difficult to modify."
Poeschel said BMW developed 5,000 lines of script code to manage Xen. The open source rdiff-backup tool is used to back up and restore virtual machine images.
By using the open source ssh-crosslogins software, the whole environment can support computational farms, he said. Since Xen does not encrypt live migration data, BMW uses SSL to transport virtual machine mirrors over a secure link. The open source md dev tool is used for disc mirroring.
BMW also produced a simple workaround for a limitation on the number of virtual CPUs a virtual machine on Xen can support. Poeschel said Xen limits the maximum number of virtual CPUs when the virtual machine is created. To overcome this limitation, BMW initiates each virtual machine with eight CPUs, then reduces the number of CPUs after a few seconds.
BMW is among the first companies to use Xen in a live production environment. Poeschel said the company needs to work closely with Novell to improve the Xen product, such as the mirroring and live migration features, which have now been fixed in SuSE Linux Enterprise Server 11 SP1.