Patent ID: 8346826

Claim:
A backup management system comprising: a plurality of file servers, each of the file servers include a file system; and a switch arranged logically between a user terminal and said plurality of said file servers, said switch including: connecting a plurality of file systems of said plurality of said file servers into a single directory tree to construct a pseudo file system, a file access to each of said plurality of file systems of said plurality of said file servers by said user terminal being performed through said switch, said plurality of said file systems constructing said pseudo file system being accessed as a single file system by said user terminal through said switch; commanding said plurality of file servers to start generation of snapshots, which are fixed images of said file systems at a certain point in time, said plurality of file servers generating respective snapshots responsive to a command that starts said generation of said snapshots; and making a connection across said plurality of said snapshots to generate a virtual snapshot, in which said plurality of said snapshots generated by said plurality of file servers are arranged to have a directory tree structure corresponding to said directory tree of said pseudo file system at a time of said generation of said snapshots and for recording and managing tree information at a junction of each pair of said connected snapshots, each of said plurality of said file servers recording and managing, as snapshot information in said file server, directory tree structure information other than said tree information at said junction of each pair of said connected snapshots, wherein at least one of backup and restore is made using said virtual snapshot, wherein said commanding said plurality of file servers to start generation of snapshots performs name resolution processing for a tree node at said junction of each pair of said connected snapshots, and said plurality of file servers performs name resolution processing of tree nodes of said directory tree other than said junction of each pair of said connected snapshots, and wherein said junction of each pair of said connected snapshots is a data structure, and comprises pointer information pointing to said connected snapshots.