The VDisks are mapped to MDisks , where M stands for managed , and the mapping is flexible, for example, an MDisk can be mapped to multiple VDisks and multiple MDisks can be combined into one VDisk. VDisks can be transparently migrated between different MDisks without disrupting application access to the VDisk. One advantage offered by this virtualization is to insulate applications and host systems from changes in the underlying storage environment. Data, at the VDisk or LUN level, can be transparently moved to a different storage device or different storage tier without the application knowing. For more information about the SVC, refer to: IBM System Storage SAN Volume Controller, SG24-6423, which is available for download at: http://www.redbooks.ibm.com/abstracts/sg246423.html?Open 5.7.2 IBM Virtualization Engine TS7510 The IBM Virtualization Engine TS7510 is a virtual tape library. The TS7510 combines hardware and software into an integrated solution designed to provide tape virtualization for open systems servers connecting over Fibre Channel physical connections. The TS7510 combines IBM server technology, disk technology and tape technology, and is designed to virtualize, or emulate tape libraries, tape drives, and tape media. Real tape resources can then be attached to the TS7510 to help address Information Lifecycle Management and business continuance. The TS7510 is designed to help customers achieve the following throughput efficiencies: Reduce backup window Improve restore process Facilitate data sharing