Katie 1 avatar image
Katie 1 asked

SQL SERVER and Virtual server

Hello everybody,

I am currently working in a virtual server environment. I am very new to the concept of virtual server. while talking about the topology, I am told is single database server(SQL SERVER 2008) and 4 vitual servers. and there are 4 different IP addresses for the virtual servers. The point where i get confused is.. there can be n number of virtual servers on with a single database server. i assume that, its kind of 4 images of the database server are set up as virtual servers(dev, test, UAT). But, what i cannot imagaine is.. does it also mean that there are 4 instances on the database servers? I know, this might be a naive question, but any clarification will help me a lot understanding,how virtualization work with the SQL SERVER or the database server

I am trying to do the research myself..but didnt come across any document that would support or provide clarity to my thought. Any document or information or explaination.. i would truly appreciate.


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Fatherjack avatar image
Fatherjack answered

Virtualisation is where a single hardware configuration has virtualisation software that allows multiple virtual server 'images' to be created. When a virtual server is created the administrator installs and operating system and the virtual server is ready to be used. These images can be connected to, via network connections, as though they were actually hardware boxes with operating systems on them. They will have their own IP addresses. These virtual servers get software installed - whether that is MSExchange for email, IIS for web servers, SQL Server for database storage or whatever is required.
The theory is that the old methodology of having dedicated hardware for each server was overkill - the CPU, HDD, RAM etc were never really utilised to their full potential. By getting a very high spec server and then making it run several different services (eg email and databases and web) then the hardware is better utilised and there is better efficiency.

It sounds as though you have one hardware server (host) and there are four virtual servers (guests). I am not certain from what you have said whether they are all set up with SQL Server installed. It is possible that you do so the one piece of hardware has 4 virtual servers each running SQL server, for different purposes - Dev, Test, UAT and presumably Production.
Having virtual servers means that each one can be worked on as though it were its own distinct box - it can be started up and shut down without effecting the others. They will share the hardware resources - so production may be busy and take a lot of CPU so test may suffer and so forth.

This is a whole industry sector in its own right so this is a very compressed explanation. Each product is slightly different in its terminology and way of managing the virtual images so getting too detailed here may mislead you. I would recommend you find your sys admin(s) and get friends with them, ask questions, research the actual product you are using and understand it. Not enough to run it but to know how it can affect your role and the databases you are managing. In the SQL side of things search out Brent Ozar (, he works for Quest currently but knows plenty about virtualisation from having been an admin prior to seeing the light and becoming a DBA(!!).

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Matt Whitfield avatar image Matt Whitfield ♦♦ commented ·
+1, but definitely worth +2
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TimothyAWiseman avatar image
TimothyAWiseman answered

From the description, it sounds like you have 4 VMs and each VM has its own instance. So that one physical machine is running 4 instances of SQL Server. But since they are in different virtual machines, they may each be a primary instance and it is possible you hav eno named instances.

Does that answer the question?

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Katie 1 avatar image Katie 1 commented ·
yes it does. Thanks Tim.
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