Server Virtualisation has been a hot buzzword for quite some time after it emerged in the early 2K's and then went into hibernate mode for a while.But now , its hotting up even more after EMC's acquisition of Vmware and , the controversial teaming up of Xensource with Microsoft pumping up a lot of furore from the open source community. But all said and done , what is Server Virtualisation from an amateur's point of view ? Well here's it.
Server Virtualisation is basically virtualising systems and consolidating hardware for better resource utilisation and maximising ROI,TCO(return on investment,total cost of ownership) . Sounds too jargon'ish ?? Hmmmm..Well in simple terms , imagine ten hardware systems hosting ten different platforms with each one running enterprise server roles. What if you had to consolidate hardware and run these 10 platforms on one/two hardware systems. Well , your fist answer would be "How about configuring a dual/quadra boot" ? Nice answer , but if you had to have all the systems up and running enterprise server models simultaneously , your answer falls flat.
The solution to this problem is :-> Server Virtualisation.
So how does it work and look like ? Well , we have more than one virtualisation vendors and its difficult to take all of them up here. But let me take the example of one of the leading(if i may say) virtualisation vendors,Vmware. Vmware has around 8 years experience in the field of virtualisation and are now a part of EMC(one of the leading storage vendors). So how does it work ? Well, there are two models to the Vmware virtualisation strategy
1 . Their virtual infrastructure that runs on a bare metal and doesnt need a host OS.This is called as the "Vmware ESX server". I would say ,this is server virtualisation in the purer sense , as it directly virtualises system services with the hardware. So this will essentially have an ESX Server running on Intel/AMD/etc and will run one or more instances of windows/unix/linux/mac etc as guest OS'es.
2 . Their virtual infrastructure server that runs on a host OS(Win,Unix) and relies on the host OS services for virtualising services within Guest OS'es. This is their older virtualisation model and is called Vmware Server / GSX Server.
So how does this work ? The Vmware infrastructure virtualises each of the services (Processor , RAM Memory , Storage , Networking , OS Services ) to each of the guest OS (virtual machines) as if they were directly accessing these services provided by the hardware.Give a thought to how this can be done .If not , wait for my next article :) .
How does this look like ? Well , i am attaching two snapshots that display two virtual machines running within my host SuSE OS.This is the Vmware GSX Server model(although it runs thru Vmware workstation).The first screenshot shows a Fedore Core 4 desktop(with a "gnome-terminal" opened) running as guest OS while the second shows a Windows 2K3 Server(hope u can c the windows explorer there).
Interesting , right ? Hmmm ,,watch this space on more on server virtualisation .Will look to throw more light on other suites in this space - Xen , Zones etc ...
