This will once more be held at the Barn Brasserie in Great Tey near Colchester for Dinner. I know you all enjoyed this visit in January and hope you will all be able to come again. It is a very pleasant venue with excellent food. Please see my separate emails for booking etc.
Please also see http://www.thebarnbrasserie.co.uk where you will find maps and menus.
In recent years, it has become increasingly popular in business and at home to use software such as "VMWare" to run more than one instance of Windows or Linux on a host machine. These systems are used for servers, to save money on hardware by running multiple server operating systems on one physical machine, or on the desktop for development and testing.
Gareth has provided me with a copy of his slides in Powerpoint format and I have exported these as PDF if anyone would like a copy please let me know.(Ed.)
Gareth explained that there was a free server version of VMware which ran on his MacMini, which uses an Intel Processor, and his whole presentation used this machine. He also used "Parallels " which enabled windows to run faster without needing a reboot.
There are various techniques to implement Virtualisation.
Hardware Virtualisation, OS Virtualisation, Paravirtualisation - the Middle ground and System Emulation.
So some applications require extra virtualisation to handle hardware differences and some require an OS virtualisation to handle processor differences or OS differences. For example running Linux on a PC or running an older version of windows on a Vista or XP OS
Hypervisor A Small piece of low level code to intercept hardware calls and provide appropriate emulation
Runs "guest" operating system unmodified Emulates known system hardware in software
Disk controller, graphics card, ethernet chip, sound etc Requires no modification of Windows / Linux etc.
Large overheads in emulating all hardware calls 20% or greater performance hit · Does not scale well to running multiple instances on a single machine
It is more suitable for desktop / testing use, not production servers. VMWare server, player and fusion use this model.
Hypervisor
This provides an abstracted API to provide physical access to hardware where possible
Requires installation of device drivers into "guest" operating system E.g. disk controller, graphics card, ethernet.
There is a perceived performance increase, improved graphics acceleration with faster disk / network access.
This gives a productivity increase with shared access to data in "host" OS via emulated shared drives. this has automatic input context switching with the ability to attach USB devices on the host into a running VM. VMWare player/server/fusion with guest tools installed.
Has a limited Hypervisor with a much smaller hypervisor than full hardware emulation
It runs on host OS as domain0 to handle I/O for multiple user domains.
It is half way between hardware and OS virtualisation and has some aspects of each.
Guest Operating Systems must be individually ported, e.g. Linux kernel support
It supports Linux host with Linux guests.
It scales well for guests that are not too intensive, e.g. static web hosting, email serving etc.
It is used quite commonly by lower end VSP market.
VMWare ESX server
The Hypervisor runs directly on native hardware, no host operating system.
Much of the "guest" runs native on CPU, hypervisor handles privileged instructions. It has much lower performance hits and is scalable. However it is expensive and therefore is usually aimed at datacenters / businesses.
Here the OS is modified to allow partitioning or running of multiple kernels in user space.
There are many examples in the UNIX space, all slightly different but following same principles
Linux on Linux
User Mode Linux
Solaris Zones / Containers
In this the Linux kernel modified to run as a user process and I/O access is via standard Linux APIs. e.g. Virtual Filesystems (mounted via loopback) and Virtual Ethernet (TAP). Linux userland within virtual filesystem unmodified, standard code, any distribution. It is another popular Linux VSP tool.
Guest instances run as restricted jails within the host filesystem. There is a standardised API for virtualised I/O similar to UML. The entire system of host and guests running single instance of kernel gives lower overheads but with a 2 3 % performance hit typically.
Running a foreign guest OS with a different cpu architecture and perhaps custom chips. There are often added complexities. There is a significant performance hit if emulating non- native architecture.
This can support virtualisation if running x86 Linux on x86. It can also emulate other systems for development / testing. Supported hosts are X86, PowerPC . and supported targets are ARM, SPARC, PowerPC, Mips, m68k.
This emulates a full x86 processor, support chipset and BIOS. It allows running of x86 operating systems on other architectures. It emulates every instruction and hence is VERY SLOW.
A conventional CPU core emulation emulates every single instruction. It interprets the same code again and again individually. A JIT core scans ahead for fragments of code that can be translated into a native set of instructions, and replaces all other instances with that faster native code. It increases performance with runtime, as it optimises. · It is significantly quicker. An example for RISC OS is RedSquirrel vs Virtual Acorn!
This company has products to virtualise RISC OS on Windows and now Mac OS X.
It emulates ARM core with JIT. and emulates the RiscPC custom chips e.g. IOMD, VIDC etc.
A HostFS provides interaction with host filing system and provides an interface to windows networking.
The formal presentation was then followed by several demonstrations.
Firstly of VMware fusion which is a Mac end Linux. Then of Ubantu.vmx which is an Opensource OS version of Linux. Gareth Installed several virtual machines. LinuxXP.vmx, mbaypline.vmx and ubantu.vmx. (I've lost some of the detail here Ed.)
Eventually Gareth was able to download these modules from the internet via bluetooth connection between the MacMini and his mobile phone. (The first time we have had an internet connection at Bourne Vale to my recollection. Very impressive!Ed.)
Gareth also showed that you could run multiple servers on XP for multiple users such that each user would only see his own file system. Another demonstration showed virtual servers can be used for helpsites from VAserve.com allowing hosting. This is a very cost effective way for say £12 /month to sell server space.
Michael also demonstrated a Virtual PC with a free version of a virtual server (VNC) on Windows. One use of these is to allow older versions of windows to be run on a modern machine. It also allows you to install Vista on an XP machine. Hardware virtualisation is not available. You can also instal several copies of XP and it is possible to run both 32 and 64 bit systems.
I would like to thank Gareth and Michael for their excellent presentations for this meeting.
We wish Tony a good recovery from his illness. Several of us paid him a visit last Saturday as it was his 77th Birthday last Thursday and he and Ann were having a party to celebrate. He was in good form and we were very impressed with his garden.
| 2007 | ||
| August 15th | Social evening at the Barn Brasserie, Great Tey | All |
| September 5th | TBA | TBA |
| October 3rd | JPEG Slideshow presentations | All |
| November 7th | What is a server? - (Microsoft based) | Michael |
| December 5th | Gadgets and party evening | All |
Talks with Visiting speakers are shown in Red. We will give more details as soon as they are confirmed. We are having a committee meeting this month to revise our programme so the above topics will probably change.
Our meetings are held at the Bourne Vale Social Club, Halifax Road, Ipswich IP2 8RE , for a map and other details please see the website. http://icenicomputerclub.users.btopenworld.com
The first visit is free and subsequent visits for non - members is £2·50. The membership fee is £20 due from the AGM date in April, but may be reduced for those joining late in the year.
Continuing our publicity for EAUG events - please see their Website for details of their next meeting.
| 18th August 2007 | "BBQ" | |
| 11th September 2007 | "Voice over Internet Protocol" | |
| 9th October 2007 | "Artworks + ?" | |
| 13th November 2007 | "Film scanning revisited" | |
| 11th December 2007 | "Xmas Special" | |
| 14th January 2008 | "What I got for Xmas" | |
| 12th February 2008 | "Sat Nav Loaded" |
Meetings are at the Great Baddow Village Hall, on the second Tuesday of the month
opening at 7:30 p.m. for a start at 7:45 - 8:00 p.m.
For directions see below (note the new web addresses)
http://www.eaug.org.uk or 'phone one of the contacts on http://www.eaug.org.uk/ppl.htm
"ICENI does not have any Insurance cover for computers or other equipment so please be advised that you bring machines to the club at your own risk."
P.S. My insurance company have added my computer cover away from home with no extra premium required, yours might do the same.(Ed.)
If anyone would like a copy of the CD of our old newsletters this could be arranged.
I am open to suggestions on what people would like to have included in the website.
Our website URL is
http://icenicomputerclub.users.btopenworld.com as a virtual domain,
it can also be reached using http://www.btinternet.com/~icenicomputerclub
Email to: iceni@woolridge.org.uk