Introduction

What is a snapshot

Snapshot technology is becoming prevalent to perform data protection and other tasks such as data mining and data cloning. Most leading storage hardware and software vendors provide snapshot support. Use of snapshot technology for data protection offers critical business value, such as zero impact backup with minimal or no application downtime, frequent backups (for example, hourly) to reduce recovery time, efficient backup of large volumes of data, reduced exposure to data loss, and instant recovery from snapshot.

Snapshot is the ability to record the state of a storage device at any given moment and preserve that snapshot as a guide for restoring the storage device in the event that it fails. A snapshot primarily creates a point-in-time copy of the data. Point in time copy or snapshot are virtual or physical copies of data that capture the state of data set contents at a single instant. Both virtual (copy-on-write) and physical (full-copy) snapshots protect against corruption of data’s content. Additionally, full-copy snapshots can protect against physical destruction. These copies can be used for a backup, a checkpoint to restore the state of an application , data mining, test data and kind of off-host processing. An important peculiarity of these copies is that from the application point of view the copy seems to occur atomically. That means that all the data updates that happens on the original data are applied before or after the point in time copy. Typically, snapshot copy is done instantly and made available for use by other applications such as data protection, data analysis and reporting, and data replication applications. The original copy of the data continues to be available to the applications without interruption, while the snapshot copy is used to perform other functions on the data.

Snapshots provide an excellent means of data protection. The trend towards using snapshot technology comes from the benefits that snapshots deliver in addressing many of the issues that businesses face. Snapshots enable better application availability, faster recovery, easier back up management of large volumes of data, reduces exposure to data loss, virtual elimination of backup windows, and lowers total cost of ownership (TCO).