Allows for multiple virtual machines to run different operating systems on the same hardware side by side
IBM had provided an IBM 704 computer, a series of upgrades (such as to the 709, 7090, and 7094), and access to some of its system engineers to MIT in the 1950s. It was on IBM machines that the Compatible Time Sharing System (CTSS) was developed at MIT. The supervisor program of CTSS handled console I/O, scheduling of foreground and background (offline-initiated) jobs, temporary storage and recovery of programs during scheduled swapping, monitor of disk I/O, etc. The supervisor had direct control of all trap interrupts.
Disappeared through most of the 80’s and 90’s even with the emergence of Java as a popular programming language, now making a comeback
- Give root to an untrusted user (e.g., student) to a virtual machine rather than the physical one - Many VMMs can save the state of a virtual machine (checkpoint) which means the virtual machine can be stopped and restarted. This allows for the real OS to be interrupted (shut down, upgraded, etc.) while long-running jobs on the virtual machine will be able to continue later. - Some VMMs can move that state to other physical machines. So imagine you have a big real system with lots of virtual machines. Some of those VMs are getting busy, and your big system is now overloaded. You can install an additional real machine, and move some of those VMs to the new real machine transparently.
We now have Windows XP running on the Intel-based Macintosh — as a guest operating system under the Linux version of VMware . This is quite exciting and promising, especially since the performance of Windows XP seems quite amazing (based on our limited test run so far) — mind you, the kernel and the environment we are using are experimental and unoptimized, so it would not be unreasonable to expect even better performance.
The Xen 2.0 system that was used at OLS 2004. We're running KDE in domain 0 (which is a Redhat 9.0 install), with VNC connections to 4 other domains visible. The other domains are running SuSE (top left), Fedora Core 1 (top right), Knoppix (bottom left) and Fedora Core 2 (bottom right).
Puppy Linux running in QEMU running in FreeBSD running in QEMU running in Windows XP
Virtualization and Virtual Machines (VM) Tom Gianos 3/29/06
Xen provides better performance (usually 2% on benchmark tests vs. 20%)
Xen doesn’t support Windows yet since it is illegal to modify Windows, more on this later
Xen takes more work to get it up and running
Xen is free and is being supported by the Linux community including Red Hat (Fedora)
Red Hat’s “Integrated Virtualization Platform”
Going to build virtualization technology right into Red Hat beginning with Fedora Core 5.0
“ This summer, Red Hat will make available Virtualization Migration and Assessment Services along with an Enterprise Virtualization beta. Red Hat Enterprise Linux 5, which the company scheduled for general availability by the end of 2006, is expected to feature fully integrated virtualization.” (searchopensource.techtarget.com)