What Is Copy-on-Write (CoW)

November 7, 2023

Copy-on-write (CoW) is an optimization strategy used in memory managementfilesystems like Btrfs, when saving the current state of a virtual machine (VM), and in snapshot and backup operations.

When an entity or process intends to modify a shared resource, the system creates a distinct copy for that entity. The original resource remains intact and available to other entities. This approach conserves system resources by minimizing redundant data replication.

By delaying data duplication until the last possible moment, the CoW approach streamlines storage and memory usage and maintains data integrity.

Anastazija is an experienced content writer with knowledge and passion for cloud computing, information technology, and online security. At phoenixNAP, she focuses on answering burning questions about ensuring data robustness and security for all participants in the digital landscape.