Virtualized Storage

The storage requirements of any organisation have changed rapidly over the past decade and even more so over the past few years. We now talk in Terabytes instead of Gigabytes and so this need grows. With it comes the need for more flexible provision and lower costs to meet those needs. Virtual Storage is the answer to those issues. So what is it?

Storage has traditionally been made up of disks inside servers... known as DAS (Direct Attached Storage). The disks were near impossible to expand and limited to what was available at the time of build. Then along came NAS (Network Attached Storage) which moved the storage outside of the box and put it directly on the network. A NAS box provides shares for users to connect to but is still relatively inflexible.

SAN (Storage Area Network) has been around for some time but was generally out of reach for many. It brings a different type of storage which is basically storage outside the box which appears to be inside the box. So SAN allows servers to have connections to storage which is not internal but appears to the server to be internal, like DAS. SAN allows many servers to connect to the same storage and to be allocated a portion of it. So you can see this is more flexible. iSCSi (over Ethernet) SAN has brought the cost of this storage down and opened the market and the possibilities for all sizes of organisation to use it.

Now introduce Virtualization technologies and we can use virtualised disks which can be resized and moved around easily, bringing endless possibilities to storage including resilient SANs which mirror data for live failover.

A typical SAN box used for virtual storage...