snapshotlist

Snapshotlist is a term used in computing to refer to a collection or catalog of snapshots representing the state of a dataset, system, or application at discrete points in time. A snapshotlist does not itself store all data; rather, it maintains references to individual snapshots and associated metadata, enabling navigation, comparison, and restoration of past states.

Each entry in a snapshotlist typically includes fields such as snapshot_id, timestamp, base_reference, parent_snapshot_id, description, size, status, and pointers to data blocks or delta sets. The list may be stored in a metadata database or as part of a filesystem, virtual machine manager, or database engine. In copy-on-write architectures, a snapshot entry records the relation to the base state and the changes made since then.

Operations commonly supported by a snapshotlist include creating a new snapshot (appending an entry), restoring the active state to a chosen snapshot, pruning or expiring older entries according to retention policies, and listing snapshots in order. Some implementations support branching, allowing multiple independent lineage paths from a common base, which is useful for testing or development workflows.

Applications of a snapshotlist span multiple domains. In virtualization, it tracks VM states for quick recovery or rollback. In databases, it enables point-in-time recovery and consistent reads. In backup systems, it serves as a registry of restore points. In certain file systems and storage solutions, snapshotlists underpin snapshot-enabled volumes for data protection.

Considerations for snapshotlists include storage overhead, performance impact from maintaining metadata, retention and lifecycle policies, data integrity, and access control. They are often accompanied by mechanisms to ensure consistency and reliability across system crashes or unexpected shutdowns.