Linux, politics, and other interesting things
I believe that an ideal installation process for Linux would have the option of performing a Xen install.
The basic functionality of installing the Xen versions of the required packages (the kernel and libc), the Xen hypervisor, and the Xen tools is already done well in Fedora and it’s an option to install them in Debian. But more than that is required.
Xen has two options for networking, bridging and routing. The bridging option can be confusing to set up and changing a system from routed to bridged networking once it’s running is a risky process. I have documented the basic requirements for running bridging in a previous post, but it would be better if there was an option to have Xenbr0 as the primary device from the initial install – and there are non-Xen reasons for doing this so it would be a more generally useful feature.
Another common requirement for a Xen server is to have a DVD image on the local hard drive for creating new DomU’s. If we are going to need a copy of the DVD on the local hard drive for Xen installation and we need data from the DVD for the Dom0 installation then it makes sense to have one of the early installation tasks (immediately after running mkfs) be to copy the contents of the DVD to the hard drive. Hard drives are significantly faster than DVDs – especially for random access. It would also avoid the not uncommon annoyance of getting part way through an install only to encounter a DVD or CD read error…
Here are some reasons for running Xen (or an equivalent technology) when not running more than one DomU:
Even in situations when reason #2 was the motivation for installing Xen I believe that most systems will want to have a Xen DomU running the same version as the Dom0 for the initial install. Therefore integrating the installation process would make things easier. Among other benefits if you have a server with multiple CPUs (the minimum number seems to be two CPUs on all recent machines) and hardware RAID then doing two installations at the same time is likely to give better performance overall. Also I believe that it will often be the case that the Dom0 will exist purely to support DomU’s, therefore if you only install the Dom0 then you have done less than half the installation!
For a manual installation there are some reasons for not doing this all at the same time. Having the sys-admin enter configuration data for some DomU’s at the same time as the Dom0 can get confusing. However for an automated install this would be desirable. I would like to boot from a CD and have the installation process take all configuration from the network (either via NFS or HTTP) and then perform the complete installation of the Dom0 and the DomU’s automatically.
Let me know what you think of these ideas, it’s just at the conceptual stage at the moment.Tags: Best Posts, Debian