In the second part of this course, you saw how to set up a test environment with a type 2 hypervisor. Although very useful, these hypervisors, such as VirtualBox, have performance limits.
In the previous example, your VMs were not always very responsive. However, it isn’t a problem for tests, as performance is not the goal. Instead, the aim is to test specific functions or compatibility.
To transform physical infrastructure (database servers, web servers, DNS servers, domain controllers, etc.) into VMs on a business network, you must ensure that you won't lose performance.
Luckily, type 1 hypervisors were created with this in mind, and in this part of the course, you’ll learn how to use the most popular: ESXi.
Set Up an Architecture for Virtualization
As a new network administrator in a company, you almost certainly won’t have to deploy a whole new virtual architecture, as there will already be one in place.
However, you should understand how it works, and for this, you need to know why companies choose virtualization.
A small online sales company employing five people will have the following network infrastructure:
A mail server.
A web server to host its website.
A NAS to store the employees’ work files and documents.
The company would like to add an authentication server (RADIUS) and a print server soon. However, considering their budget and the limited space available in the comms room, they decide to invest in a machine with 32GB of RAM, a 3.2GHz processor with six physical cores (12 logical cores), and 1TB of disk space.
This machine will be used as the hypervisor and will initially host:
A mail server VM
A web server VM
And then later on:
An authentication server VM
A print server VM
NAS is an independent physical device for storage on multiple physical hard drives. Therefore, it cannot easily be virtualized.
The same applies if you have a machine that needs a huge amount of resources and will take up more than 75% of the host machine’s resources. Virtualization will be of little use in this case, and you run the risk of slowing down the other VMs using the same hypervisor.
Let’s go back to our example. This is what your network will look like after virtualization:
To design your architecture, you should ideally:
List the number of services/functions on your network.
Define what services/functions can be virtualized.
Estimate the resources necessary for each service:
Storage
RAM
CPU
Network
If your company has a monitoring tool such as Nagios, it’s a good idea to use it to confirm your resource estimates. For example, list the number of VMs to be created and check that one virtualization server (hypervisor) is enough to host them all – otherwise, you’ll need to invest in a second one.
Sometimes, several entirely different services are installed on one physical machine to save money. For example, the Apache service for the web server and the bindService for the DNS server might be installed on the same machine. This machine then becomes both the web and the DNS server.
You can understand why people who aren’t familiar with virtualization might do this. However, there is a risk that if a problem occurs with one of the services, it will affect the other and have a larger impact than if they were on two separate servers.
The advantage of virtualization is that you can segment the services by placing them on a different VM and create as many as you need!
Let’s put all of this into practice by installing the ESXi hypervisor.
Let’s Recap!
You must not lose performance when migrating physical infrastructure to VMs.
Mount the ISO onto the VM. The installation will then begin when the VM is powered on.
When designing your virtualized infrastructure, you should:
List the services on your network.
Define what services can be virtualized.
Estimate the resources necessary for each service.
This chapter has helped you understand them. In the next chapter, you’ll learn how to create a virtualized environment using ESXi once you have made these considerations.
