METHOD FOR EXECUTING SNAPSHOT FOR LARGE SCALED COMMON STORAGE

摘要

PURPOSE: A method for executing snapshot for a large scaled common storage is provided to support online backup for large scaled logical volume based on an SAN(Storage Area Network). CONSTITUTION: Mapping converts logical address to physical address, and offers independence between logical address(402) and physical address(403) thought free space manager. Each mapping entry(401) comprises an FAB(First Allocation Bit, 407), an SSB(Snapshot Status Bit, 408), and the physical address(403). The FAB(407) discriminates a first located/used data block after snapshot. After generating snapshot, the data block is located by the free space manager. The FAB value is changed to '1' when the data block is used, and the mapping entry(401) is recorded on the disk. The SSB(408) shows a snapshot status. The FAB(407) and the SSB(408) is initiated when the physical volume is generated at the common storage.