Understanding Storage Virtualization

In the early days of the personal computer, data was saved to floppy disks and enterprise data stored to reels of magnetic tape. A lot has changed since then. Today, personal computers and laptops come with a tremendous amount of disk space on traditional or solid state disk drives. In network environments, data is stored on network-attached storage devices, RAID arrays, storage area networks, or "in the cloud".

While it is now possible to store massive amounts of enterprise data on hundreds, if not thousands of hard disks, those disks must be managed and supported. That's where storage virtualization comes in. Storage virtualization typically pools physical storage devices together, even if those devices are from different vendors. Storage virtualization creates a virtual layer between the aggregated storage pool and servers. Applications are no longer limited to fixed storage devices and they do not need to know the precise drive, partition, or sector where the data is stored.

From an administrative perspective, the distributed storage is managed and provisioned as a single resource. From a server's perspective, the storage virtualization layer is its only storage device. Likewise, from each storage device's perspective, the virtualization layer is perceived as its only server – even if hundreds of servers store and access data on the device.

Several approaches to storage virtualization exist including host-based, device-based, and network-based approaches.

· Host-Based Storage – With a host-based approach, a device driver handles the physical drives while a software layer handles I/O requests and redirects.

· Device-Based Storage – Some advanced RAID storage devices allow for additional storage devices to be added, allowing storage virtualization to take place at the device level. These systems typically include hardware or switches to handle pooling.

· Network-Based Storage – Network-based virtualization typically use hardware appliances or switches to create a storage area network that is viewed as a single network-based storage device.

Benefits of Storage VirtualizationJust as other virtualization strategies, such as moving to a virtual desktop infrastructure, can be beneficial, the same is true of storage virtualization. Benefits include:

· Simplified storage management – Administrators use a single interface to manage and support storage devices.

· Ability to group diverse storage systems into tiers – Devices from multiple vendors can be added and grouped into tiers.

· Reduced need for manual provisioning – Storage capacity can be expanded and automated without the need to manually provision new devices.

· Improved performance and reduced downtime – Updates and maintenance can take place as needed with minimal impact on performance and downtime.

· Background data replication services – Storage virtualization systems can handle data replication in the background.

· Hot-swappable disks – With storage virtualization, applications and servers are shielded from the storage environment and data can be moved from one device to another without impacting operations. Administrators can hot swap disks or move data to other devices without affecting data access.

Storage virtualization adds an intermediate layer between server and storage systems. As a result, it simplifies disk management, support, and data access while also improving performance, reducing downtime, performing background data replication services, and more.