File replication method for distributed file systems

A replication system for performing file replication between a plurality of network storage apparatus connected to a network, said replication system comprising:

• a management table for managing attribute information of all files and directories in the network storage apparatus as a replication source;
• a unit for holding replication information indicative of whether or not replication should be performed;
• a request reception unit for receiving, a file access request from a client;
• and
• a replication unit for simultaneously transferring the file access request to the plurality of network storage apparatus, said replication unit including
• a judgment unit for judging whether or not replication should be performed by using the management table and the replication information and
• a request processing unit for simultaneously transferring, in accordance with a result of the judgment, the file access request to the network storage apparatus as the replication source and to the network storage apparatus as a replication destination.

A file replication method for creating, in an external network storage, a partial copy of data stored in a virtualized-and-unified file system including a plurality of network storages and a unification virtualizing system for managing, in a unified manner, a structure of files and directories present in distributed relation in the network storages and attribute information thereof and allowing a unified access to the network storages from an outside, said method comprising the steps of:

• preliminarily recording, in said unification virtualizing system, replication information specifying the file as a target of replication;
• receiving, in a unified manner, a file access request from a client to said virtualized-and-unified file system;
• specifying the network storage storing therein the file as a target of said file access request by using a mapping unit for determining and setting the network storage for each of the files;
• judging, by using said replication information, whether or not a replicating operation should be performed with execution of said file access request;
• and
• transferring said file access request to the specified network storage and, if a result of said judgment is such that the replicating operation should be performed, transferring the file access request also to the external network storage as a replication destination, and thereby causing each of the network storage storing therein said target file and the external network storage as the replication destination to execute a file access requested by the file access request.

A unification virtualizing system for a plurality of network storages, said system virtually showing the plurality of network storages connected to a network as a single file system and comprising:

• a unified management directory for managing a structure of all files and directories present in said virtualized-and-unified file system and attribute information thereof;
• a unit for holding replication information for specifying the file to be replicated by assuming that an external file system is a replication destination;
• a request reception unit for receiving a file access request from a client;
• a mapping unit for determining the network storage of a file access target of said file access request;
• a judgment unit for judging whether or not the file access target of said file access request should be replicated in said external file system by using the unified management directory and the replication information;
• and
• a request transfer unit for simultaneously transferring, if the judgment unit judges that replication should be performed, said file access request to the external file system as the replication destination and to the network storage determined by the mapping unit.