Virtualization 101

virtualization-101Many folks that work in high-tech have a tendency to get so absorbed in their own technology or work (a.k.a. “the Kool-Aid”) that they often leave the rest of the world behind in day-to-day conversations. We at Silver Peak were even called out for this in a front page San Jose Mercury News article back in March titled “Geek-speak stumps the nontechies.”

The truth is that not everything is intended for your grandmother. Einstein once said “everything should be made as simple as possible but not simpler.” In the spirit of that, we come to the topic of virtualization. While the excitement and buzz around virtualization is at an all-time high, there are still lots of questions swirling in many different circles (including enterprise IT) about what virtualization is and how it can help.

To soften the blow a bit for those who may not know or just want more information, here are a few frequently asked questions and answers about virtualization for corporate or enterprise IT.

What is the general advantage of virtualization?
hardware-to-virtualizationThe general concept of virtualization is that the operating system and application combinations that used to require multiple, dedicated servers can now be consolidated to run on a single server.

What are three typical benefits of virtualization?
Cost – lower price, subscription, no shipping & installation, no hardware refresh, upgradeable.
Flexibility – deploy, move, upgrade, add, change, deploy in cloud, etc  “on the fly”
Availability – More efficient backup/disaster recovery; abstracts software from hardware (failures).

What are the fundamental components of a virtual architecture?
Application: The software that runs on an operating system.  Examples include the software that most of us interact with on a daily basis (Microsoft Word, Outlook, Excel, etc.), databases (Oracle, SQL, etc.), replication software (Double-Take, Netbackup, etc.), financial applications (Navision, SAP, etc.), and basically any other software that is not an operating system.
Operating System: The software installed on any hardware that controls all of the basic functionality (keyboard, mouse, networking, etc). Examples include Microsoft Windows and Linux. Applications run on top of an operating system.
Host:  The physical hardware (laptop, PC, server, etc.).
Hypervisor: The software that allows multiple virtual machines to run on one host.
Virtual Machine: The individual “machines” that run on the hypervisor. Each virtual machine is equivalent to a single PC with an operating system (Windows, Linux) running one or more applications.
Virtual Appliance: A virtual appliance is a special instance of a virtual machine where the application and operating system are packaged together.  Virtual appliances tend to perform specific functions. Silver Peak’s VX products are all virtual appliances.
Cluster or Data Center: A collection of physical hosts.
Management Server: A stand-alone server that manages all the virtual machines running on all the hosts in a data center.
Management Client: The user interface to the management server through which all virtual machines in a data center are managed.

How is virtualization applied in a data center?
Multiple instances of the virtual architecture building block shown above can now be clustered together to build a data center. The resulting large number of virtual machines requires management software to allow the administrators of these virtual machines to manage them effectively. The diagram below shows a data center and the necessary management components.


What is VMware vSphere?
VMware vSphere is the name of the entire virtualization platform from VMware, a leading virtualization company. Below is a list of the most relevant vSphere components.

Hypervisor:  VMware vSphere Hypervisor (ESXi)
Management Server:  vCenter Server
Management Client:  vSphere Client

Below is a screen shot from the vSphere Client that shows how the various components of a virtual architecture are presented.


Is the vCenter Server always required?
No. For the simpler case where there is only one host, the vSphere Client can connect directly to the host and manage all of its virtual machines.  See diagram below.

Where can I get the free version of the VMware hypervisor?

What’s the difference between the free and paid version of the VMware hypervisor?
The free version operates standalone only and cannot be added to vCenter or put in any VMware data center deployment.  It does not support vMotion.

What is vMotion?
vMotion is the ability to move virtual machines from one host to another by simply dragging and dropping them in the vSphere client.  This is shown in the diagram below.

What is an OVA?
An OVA, open virtual appliance, is the general name of the files that contain virtual appliances such as the Silver Peak virtual WAN optimizers. The OVA is deployed through vSphere to create a virtual appliance.

Other helpful links:
Free VMware Hypervisor
Free XenServer Hypervisor

Special thanks to Silver Peak virtualization product manager Vivian Xu and VP of engineering Carl Hubbard for the heavy lifting here and getting the conversation started!