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If you want a reliable network then you need to determine an appropriate level of redundancy. When servers were small and there was no well accepted virtual machine technology there were always many points at which redundancy could be employed.
A common example is a large mail server. You might have MX servers to [...]

Today a client asked me to advise him on how to dramatically reduce the number of servers for his business. He needs to go from 18 active servers to 4. Some of the machines in the network are redundant servers. By reducing some of the redundancy I can [...]

Yesterday I wrote about my search for a hosting provider for a Xen DomU [1]. One response was the suggestion to run a Dom0 and sell DomU’s to other people [2], it was pointed out that Steve Kemp’s Xen-Hosting.org project is an example of how to do this well [3]. Unfortunately Steve’s service [...]

I’m currently deciding where to get a Xen DomU hosted. It will be used for a new project that I’m about to start which will take more bandwidth than my current ISP is prepared to offer (or at least they would want me to start paying and serious bandwidth is expensive in Australia). [...]

The first step is to copy /images/xen/vmlinuz and /images/xen/initrd.img from the Fedora (or RHEL or CentOS) DVD somewhere convenient, I use /boot/OS/ (where OS is the name of the image) but other locations will do.
Now choose a suitable Ethernet MAC address for the interface (see my previous post on how I choose them [1]).
Create a [...]

The way Xen works is that the RAM used by a virtual machine is not swappable, so the only swapping that happens is to the swap device used by the virtual machine. I wondered whether I could improve swap performance by using a tmpfs for that swap space. The idea is that as [...]

I’m currently in Xen hell. My Thinkpad (which I won’t replace any time soon) has a Pentium-M CPU without PAE support. I think that Debian might re-introduce Xen support for CPUs without PAE in Lenny, but at the moment I have the choice of running without Xen or running an ancient kernel on [...]

I’m setting up a training environment based on Xen. The configuration will probably be of use to some people so I’m including it below the fold. Please let me know if you have any ideas for improvements.
The interface for the user has the following documentation:

sudo -u root xen-manage create centos|debian [permissive]
Create an image, [...]

I have previously posted about the difference between using a chroot and using SE Linux [1].
Theo de Raadt claims that virtualisation does not provide security benefits [2] based on the idea that the Xen hypervisor may have security related bugs.
From my understanding of Xen a successful exploit of a Xen system with a Dom0 that [...]

I am currently considering what to do regarding a Zope server that I have converted to Xen. To best manage the servers I want to split the Zope instances into different DomU’s based on organisational boundaries. One reason for doing this is so that each sys-admin will only be granted access to the [...]