Snapshot

A snapshot is a representation of the state of a system at a specific point in time. In computing, snapshots preserve data and configurations for purposes such as backup, rollback, replication, testing, or analysis. They may cover storage content, file systems, databases, virtual machines, or memory, and are typically designed to be quick to create and to minimize additional storage until changes occur.

The term comes from photography, where a snapshot is a quick photograph of a scene. In computing, snapshots often use copy-on-write or similar techniques, allowing the snapshot to reference existing data and only allocate new storage when data changes.

File system snapshots capture the state of a file system at a moment. They enable point-in-time backups and fast restoration; they are commonly asynchronous or integrated with storage arrays and operating systems such as ZFS, Btrfs, APFS, and Windows or Linux file systems.

Database snapshots provide a read-only or time-based view of data, supporting reporting or point-in-time queries. Virtual machine or disk snapshots capture the entire VM state or disk contents, enabling quick rollbacks or cloning. Memory snapshots record a process’s or system’s memory at a moment, useful for debugging and crash analysis. Cloud environments often offer snapshot services as part of storage or compute platforms.

Uses include data protection, testing and development, and forensic or audit tasks. Limitations involve ensuring consistency during capture, potential performance overhead, storage costs, and the need to manage retention and dependencies between snapshots.