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For the purposes of our review of these companies' activities, a virtual storage system is defined as one that virtualizes block disk storage behind it. The virtualization products support heterogeneous storage devices and can pool disk storage from any supported attached storage.
Of course, there are several different ways to implement storage virtualization: on the host, in the SAN or at the controller. Block virtualization redirects an I/O request from a virtual location to a physical location, so data can be moved anywhere within the virtualized storage pool transparently to applications and users.
Other features common to virtual storage systems include:
- Snapshot or point-in-time copy across disparate or similar storage devices
- Remote replication across disparate or similar storage devices
- Data migration from one back-end disk group to another while applications continue to access the data
- Centralized management of all virtualized storage
This was first published in August 2006