For the computer systems, snapshot means the system state at a particular point, and it is commonly used in backup & restore solutions. A snapshot backup performs a virtual copy of file system or raw logical volume in which the file system or raw logical volume stays active and available for reading and writing operations during the backup, it is not a copy of the data, only a picture in time of how the data was organized.
Snapshot is a read-only copy of the data set frozen at a point in time, which also allows applications to continue writing to their data. It can be completed in a very short time. Most snapshot implementations are efficient and can create snapshots in O. In other words, the time and I/O needed to create the snapshot does not increase with the size of the data set, whereas the same for a direct backup is proportional to the size of the data set. In some systems once the initial snapshot is taken of a data set, subsequent snapshots copy the changed data only, and use a system of pointers to reference the initial snapshot. This method of pointer-based snapshots consumes less disk capacity than if the data set was repeatedly cloned.
Comparing with the full backup, snapshot backup owns advantages below:
Snapshot can be completed in a very short time, and before the following issues happen, you need to do snapshot backup to protect operating system:
Sometimes, computer users have to do the operation which is not very safe, such as installing unknown software which may be dangerous to your system. If system error happens, snapshot you have done before can help your system restore to the previous state.
Trying out new applications may bring out many problems, especially for software developers who should try a lot of programs every day. Before new software test, do a quick backup will protect system perfectly.
Unpredictable disaster always happens making system fail to boot, backup is a good habit to ensure system to be recovered successfully. Snapshot helps you restore system state to a particular point you need.
Some backup software, such as EaseUS Todo Backup, which provides snapshot backup to back up your system state easily.