Benefits of virtualization for Small Businesses: Virtual Disk(s)

Virtualization is a cost effective way to maximize the IT dollars spent on hardware and infrastructure. This new series will talk about the benefits of virtualization for small businesses. We are starting on the benefits of Virtualization at the disk layer because a lot of flexibility and cost savings can be gained here.

The hard disks of virtual servers are presented in a manner that provides increased flexibility. Traditionally, a physical server's hard disk stores thousands of files and folders that is required for each specific server instance. These files make up the OS (Operating System), installed applications, and of course the data that the server requires to fulfill its purpose.

In the case of a virtual server, all of these same data elements are still required to be available. However, all of these files are encapsulated into a single, much larger file. To the virtual server, this single larger file represents a physical hard drive.

• File relocation: Because of the way the data is encapsulated into a single disk file, relocating a server from one host is as simple as moving that file to a new host, or a new filesystem on the existing host. Some small configuration files may be required as well, but the bulk of the configuration is included with the virtualized disk file.
• File copy replication: Because of the ability to easily relocate files, you can also duplicate complete server images simply by copying the files to another location. This can help you with load balancing, migration to newer, faster servers, or simply creating a cookie-cutter base server image. This is also a great way to create a test environment from a production image simply by replicating production to another location you can test run your implementation plans or new software upgrades.
• File snapshots: Today, most virtualization platforms now include the ability to "snapshot" the servers disk file. This process creates a second disk file that is connected to the first disk image. When this process is in place, all changes to the original disk are instead written to the second disk file creating an original and delta image. This is a great way to run an upgrade, but not commit your changes. In the event that the upgrade does not go as expected you can simply rollback to the first disk image, taking the system back to its pre-snapshot state. After a period of time, should it be determined that all patches were successful, you can merge the disk images back together to a "committed" state, thus eliminating the separate deltas.
• Single-file backup and guaranteed restore: Backups of physical servers have always been an area of concern with IT administrators. In a traditional environment, thousands of files making up a typical server must be backed up with the risk that loss of a single file can prevent the successful emergency restore of that server. To make matters worse, backup software may miss files simply because they are locked or in use. The combination of thesse two problems makes the successful restore of a failed server difficult, often times resulting in loss of data. Virtual disk files make this easy, because a single disk file must be backed up.
• Inexpensive disaster recovery: Small Businesses have struggled greatly with disaster recovery due to the historically high costs and oeprational complexities of managing a secondary off-site data center containing duplicate servers and hardware. Virtual servers and their disk files allow this to become a lower cost feasible option for small businesses. The main reason is that all you need is the virtual disk image and hardware to run it on. One of the main drivers for the high costs before was that hardware had to be exact, but not so with virtual servers. Because of the design of the hypervisor, specific, industry standard devices are presented to the OS, no matter what the real hardware is. Because of this, the virtual servers can be moved to different hardware.

Please tell us your thoughts and experience.