Each time the utility is run, a snapshot is created of the entire volume, not only new or updated data. Every copy-on-write process requires one read and two writes data needs to be read and written to a different location before it's overwritten.Ĭlone or split-mirror snapshots reference all the data on a set of mirrored drives. However, all previous snapshots must be available if complete archiving or recovery of all the data on a network or storage medium is required.

The data in a copy-on-write snapshot is consistent with the exact time the snapshot was taken, hence the name copy-on-write. This enables the rapid recovery of a system in the event of a program malfunction. These snapshots are created almost instantly, with little performance effect on the system taking the snapshot. There are several other types of storage snapshots:Ĭopy-on-write snapshots store metadata about the location of the original data without copying it when the snapshot is created. Not all snapshots are based on differencing disks.

Snapshots can also be useful for reverting a system back to a previous state if a bad patch has been installed. A storage snapshot can be used for disaster recovery (DR) when information is lost due to human error. Snapshots are generally created for data protection, but they can also be used for testing application software and data mining. Each snapshot taken creates another branch of the tree. Snapshots have parent-child relationships and form a tree. File systems continue to function just as they would on a physical machine. The file system is completely unaware of the existence of a differencing disk. All future write operations are directed to the differencing disk, leaving the original virtual hard disk in an unaltered state. When an administrator creates a storage snapshot, the underlying system creates a differencing disk that's bound to the original virtual hard disk. A differencing disk is a special type of virtual hard disk that's linked to a parent virtual hard disk. Storage snapshots are often based around the use of a differencing disk. A snapshot acts like a detailed table of contents, providing the user with accessible copies of data that they can roll back to. A storage snapshot is a set of reference markers for data at a particular point in time.

Drive snapshot 1.45.0.17699