Sunday, September 27, 2015

Understanding Virtualization

Understanding Virtualization

Virtualization allows multiple servers to operate on a single physical host. They provide
increased availability with various tools such as snapshots and easy restoration.

Virtualization is a technology that has been gaining a lot of popularity in recent years. It allows
you to host one or more virtual systems, or virtual machines (VMs), on a single physical system. With today’s technologies, you can actually host an entire virtual network within a single physical system and organizations are increasingly using virtualization to reduce costs.
When discussing VMs and studying for the CompTIA Security+ exam, you should understand the
following terms:

Hypervisor. The software that creates, runs, and manages the VMs is the hypervisor. Several
virtualization technologies currently exist, including VMware, Microsoft Hyper-V, Windows
Virtual PC (VPC), and Oracle VM VirtualBox. All of these have their own hypervisor

Host. The physical server hosting the VMs is the host. It requires more resources than a
typical system, such as multiple processors, massive amounts of RAM, fast and abundant hard
drive space, and one or more fast network cards. Although these additional resources increase
the cost of the host, it is still less expensive than paying for multiple physical systems. It also
requires less electricity, less cooling, and less physical space.

Guest. Operating systems running on the host system are guests or guest machines. Most
hypervisors support several different operating systems, including various Microsoft
operating systems and various Linux distributions. Additionally, most hypervisors support
both 32-bit and 64-bit operating systems.
Patch compatibility. It’s important to keep VMs patched and up to date. Patches applied to
physical systems are compatible with virtual systems.
Host availability/elasticity. Elasticity refers to the ability to resize computing capacity based
on the load. For example, imagine one VM has increased traffic. You can increase the amount
of processing power and memory used by this server relatively easily. This allows you to
ensure it remains available even with the increased demand.

Snapshots provide you with a copy of the VM at a moment in time, which you can use as a
backup. If the VM develops a problem, you can revert the image to the state it was in when you took
the snapshot. You are still able to use the VM just as you normally would. However, after taking a
snapshot, the hypervisor keeps a record of all changes to the VM.

Administrators commonly take snapshots of systems prior to performing any risky operation.
Risky operations include applying patches or updates, and installing new applications. Ideally, these
operations do not cause any problems, but occasionally they do. By creating snapshots before these
operations, administrators can easily revert the system to the previous state.

Note: Virtualization allows multiple virtual servers to operate on a single physical
server. It provides increased availability with lower operating costs.
Additionally, virtualization provides a high level of flexibility when testing
security controls, updates, and patches because they can easily be reverted
using snapshots.

From Darriel Gibson's Sec + Book

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