Last week I wrote a roundup of the virtual machine-like
technology available for Linux, and an alert reader pointed out the
User-mode Linux project.
Think of User-mode Linux (UML), a modification to the Linux
kernel that's released under the GNU General Public License, as a
cross between the VMware workstation product that allows users to
run Linux and Windows side-by-side and larger virtual machine-type
products that allow dozens of Linux copies to run on one server.
Jeff Dike, leader of the project, says users have reported running
as many as 50 virtual machines on one piece of hardware.
Here's Dike's description of a virtual machine, probably better
than I can explain it, from an article published in Linux Magazine
: "(Virtual machines) offer the ability to partition the resources
of a large machine between a large number of users in such a way
that those users can't interfere with one another. Each user gets a
virtual machine running a separate operating system with a certain
amount of resources assigned to it. Getting more memory, disks, or
processors is a matter of changing a configuration, which is far
easier than buying and physically installing the equivalent