- When I used to be a Network Manager at a university,
we had a server farm.
And in that server farm,
we had these massive servers from Dell,
they had lots of storage, lots of memory.
And we would give a job to each of those servers.
Maybe we had a Microsoft Windows Server, a Linux server,
maybe an Oracle Solaris server,
one thing we did is we gave a big server
to each college in the university.
So the College of computer science would have a server,
the College of Natural Science would have a server
and so on.
And you know what we noticed,
most of the resources were going unused,
only a fraction of that service capacity
was being tapped by the users.
Meanwhile, we had to buy all those servers,
we had to keep the operating system patches updated.
We had to provide power
and redundant power to those servers.
It wasn't cost effective.
We had so much capacity that was simply being wasted.
That's the beautiful thing about virtual machines.
Instead of having all these physical servers,
what we could do is virtualize those servers,
we could have a virtual server that contains multiple VMs,
multiple virtual machines,
we could take the Microsoft Windows Server
and the Linux server and the Oracle Solaris server
and put their hard drives on a big physical server.
And this physical server would run a virtual instance a VM,
a virtual machine,
for each of those formerly physical servers.
And those virtual servers,
they would have a virtual network interface card
to get out to the rest of the world.
And they would connect into a virtual switch,
inside of our server,
And then that virtual switch
could connect out to the physical network interface card,
of the server,
and we could connect out to an Ethernet switch.
And that would get us out to the rest of the world.
But how is this possible?
How can we take something like a Microsoft Windows server
running all sorts of applications
and virtualize that inside of a big physical server?
Well the way we can do that is run some software
on that big physical server
that's, housing all of those virtual machines.
And that software that allows us
to install virtual instances of servers,
that's called a hypervisor.
A hypervisor is able to create a virtual machine,
it can start, stop,
it can monitor what's happening with our virtual machines.
And we need to know about two different types
of the hypervisors.
Types one and two.
First of all,
type one is where we install the hypervisor software,
like an operating system directly on the underlying hardware
of the physical server.
This is sometimes called native or bare metal,
because we're not putting it on top of something
like Microsoft Windows.
Note, we're installing it directly on the machine
just like we were installing Microsoft Windows.
Well, here we've had inserted our DVD
of a hypervisor software.
And although the exam blueprint doesn't tell us
that we need to know about specific hypervisors.
Let me give you just a couple of examples.
A couple of examples of type one hypervisors
would be Microsoft's Hyper-V, VMware ESXi,
but sometimes, we have, maybe a laptop
and we'd like to run a virtual machine on that laptop.
Or for some other reason,
we want to install a virtual machine
on an existing operating system.
We can do that with a Type two hypervisor.
This is also known as a hosted hypervisor.
For example, we can install VirtualBox on Microsoft Windows,
and on top of that VirtualBox hypervisor software,
we could then install maybe another instance
of Microsoft Windows,
or maybe on a Mac,
we could install, the parallels hypervisor software
that runs on macOS.
And on top of that,
this is what I frequently do is I'll use parallels on my Mac
and install Microsoft Windows on top of that.
So if I have an application that just runs on Windows,
and I'm on my Mac,
well, I can just fire up that virtual machine
and run it in Microsoft Windows
running on top of that parallels type two hypervisor.
And that's a look at how we can use hypervisor software
to run virtual machine instances
and in our next video,
we want to take a closer look at those virtual machines.
They don't have to be just servers.
They could be other network appliances.
And we'll also go out to a type one hypervisor,
specifically VMware ESXi.
And I'll show you how to create a virtual machine.
So join me in that video next.