Why do servers run multiple operating systems through virtualization?

Question

I understand what virtualization is and its use for your average computer hobbyist, but what is the need for running multiple instances of Windows on for example a blade server?

Answer 1

It's used as a means of separation for multiple services (usually conflicting ones).



For example an organization might have license for 2 different kinds of the same product, like AutoCAD which use the same authentication system. The two versions cannot exist on the same Windows installation so they would be split across 2 machines so they didn't conflict



Organizations often use virtualization when dealing with 3rd party vendors who use client server software. This means that the techs from each 3rd party can remote into the server dedicated to their software and play around or break things and not affect the whole company.



Staging and Development is also another cause for it's use, duplicating a live server environment and running tests for upgrades or changes saves you from making mistakes on the live side.



Load balancing, sometimes you need more processing power to cope with the volume of traffic using a particular service (application gateway for example), being able to seamlessly direct traffic to two machines instead of one makes sure there are less queues.

Answer 2

What if you have a web-application or a web page. You have 'web runner' software that is automated and can exercise a local copy to look for problems.



But you now have 20 versions of internet Explorer, 30 flavors of Chrome, Firefox, Opera, Edge, etc., that you have to test. (Lets not forget mobile ports like Android, Silk etc.)



How do you test your webapp on all of these? Then repeat the tests every week to make sure the changes did not break the core functionality of your app?



Or a more evil use:



You open up an India Marketing company. People who create YouTube channels now pay you $5,000 - $20,000 to create thousands of views or subscribers on YouTube, Instragram, Facebook, Snappchat, Twitter, etc. To 'hide' your fake activity you rotate through several different operating systems (Android, iOS-on-portable, Chrome, Windows, Mac. etc) to use a database of accounts to help promote someones social media. It's not illegal if you call it 'marketing' and run from another country.



A MORE COMMON USE



You usually do not mix several operating systems on a blade server unless you have to because of some software requirements. You usually create a database-cluster on some of the blades under say RedHat Linux (because that is the recommended OS for Oracle or some-such), then some search-engine clusters using Umbuntu or CentOS, then have all your tomcat/webservers software running on the rest of the blades.



Managing all the images is tricky, but software like Chef let you create 'recipes' that can create 1-1,000 new hosts in a few minutes.

Answer 3

Security, stability, management, app separation, flexibility.

Answer 4

Sandboxing, an IT adoptation of the same sandboxing idea that Java popularizes.

Answer 5

to know good or bad of people