ABSTRACT
Snapshots play such a large part in virtual infrastructure protection that people could arguably say a full machine snapshot is the holy grail of system administration. While volume management systems (e.g., veritas volume manager, logical volume manager microsoft) have offered snapshot capabilities for some time, and snapshots are also readily available at the SAN and NAS level, these have usually had one substantial frustration: being divorced from the operational or configured state of the host they’re associated with. Equally, a raw disk is one where storage is presented directly to the virtual host without any virtualization layer involved, and is typically done so for specific performance requirements. Finally, and particularly in support of virtualizing systems that require clustering, virtualization systems can also support shared disks, where a virtual disk is presented to virtual servers simultaneously. Virtualization offers a neat way around that—multiple guest systems running on a single piece of hardware with the hypervisor directing cooperative use of system resources.
