Method and Computer System for Sharing Objects

A computer for sharing objects another computer that is coupled to storage apparatus for providing a shared namespace to store the objects including at least directories, the computer comprising:

• an interface that is coupled to the storage apparatus and a client;
• a memory being configured to store management information including local-lock counts for each of directories, the local-lock count being the number of locks taken by operations to the objects including the directory and sub-objects thereof;
• and
• a processor that is coupled to the interface and the memory,
• the processor being configured to, every time receiving a request for processing a target object from the client, request the storage apparatus to lock a parent directory of the target object if the parent directory has not been locked by the storage apparatus,
• the processor being configured to send a response of the received request to the client regardless of whether or not the parent directory has been unlocked by the storage apparatus, and
• the processor being configured to, if the local-lock count of the parent directory is zero, request the storage apparatus to unlock the parent directory.

A method for sharing, by multiple front-end nodes that are coupled to clients, objects including at least directories managed in a namespace provided to the multiple front-end nodes by a back-end node, the method comprising:

• managing, by a first front-end node that is any one of the multiple front-end nodes, local-lock counts for each of directories managed by the first front-end node, the local-lock count being the number of locks taken by operations to the objects including the directory and sub-objects thereof,
• every time receiving a request for processing a target object from a client that is coupled to the first front-end node, requesting, by the first front-end node, the back-end node to lock a parent directory of the target object if the parent directory has not been locked by the back-end node,
• sending, by the first front-end node, a response of the received request to the client regardless of whether or not the parent directory has been unlocked by the back-end node, and
• requesting, by the first front-end node, the back-end node to unlock the parent directory, if the local-lock count of the parent directory is zero.