jeff on 21 Jun 2008 14:02:47 -0700

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Re: [PLUG] Why Virtualize?

Casey Bralla wrote:
> I've been thinking about virtualizing on servers.  Although I know that 
> virtualized servers are the "next big thing", I can't for the life of me 
> figure out the advantage for virtualizing servers, except for a few very 
> narrowly specific situations.  

Funny you should mention it.... I'm with consultants doing a `VMware 
Jump Start' last week and a bit next week.  After that, we're gonna 
start going live.
This is my blog.  Up at the top is a static page called Let's Get 
Virtual.  It's the overview of our experience, filtered through my own 
uniquely skewed view.

> This saves energy because a single fully loaded server 
> requires less electricity that dozens of partially loaded servers. 


> maintenance, etc.  (Cooling costs will only go down in proportion to 
> electricity consumption, so not as dramatic a savings there.)

Going from about 20 to about 4 is fairly significant.

> But why not simply run dozens (hundreds?) of server **instances** on the same 
> server?   

hardware isn't set up for it?

Can you imagine running even *two* instances of 2003 Server on the same 

> Why add the extra overhead of the virtualization process to the 
> hardware?   That has to cut efficiency by at least a few percent.

Processor horsepower has gone up dramatically.  We're using servers with 
AMD's that are optimized for this.  Technically there will be overhead, 
yes.  This way is superior to the no hypervisor method (VMware player).

Speaking of Player, I have run three instances of player on my main 
Xubuntu box at work with little CPU use.  Starting them up sucked up 
resources but once they were up, they behaved.  One pig of a client OS 
can make a difference (XP anyone?), depending on resources allocated.

> So what is the advantage of running a complete virtualized server instead of 
> multiple server processes?

Here's our decision path:

Among our roughly 20 servers are at least 5 that are past end of life.
After one month of monitoring, we found out we were only using something 
like 10% of our hardware.  VMware has Magic Math<tm> that figures out 
from the monitoring how many servers to recommend for virtualization.

I was skeptical (because I was awake) but the numbers have been verified 
independently and we're not exactly the first company to do this.  When 
our numbers were plugged in to the handy TCO Analyzer, the three year 
cost of staying the same wildly trumped virtualization.  The C*O 
hierarchy went right for it.  Who was I to argue?

> But other than this specific case, what the heck is the advantage?

Hardware becomes standardized, which can be huge if you have to 
troubleshoot it.

You can set up a totally separate lab environment.

Backup takes on new dimensions.  There are all sorts of interesting ways 
to do it.  You can take an image of a running server and keep it 
offsite.  How's that for disaster recovery and backup in one?  With the 
copy, you can operate on live data without hurting the production 

Need a new server?  Provided you have the licensing, you make one from 
the template you create.  If you want linux, you don't need licensing 
(evil and obvious laughter).  In minutes.  Presto.

... Electronics Rule #2: never solder in shorts
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