Geographical distributed storage system based on hierarchical peer to peer architecture

A storage node for use in a geographically distributed storage system which includes a plurality of logical storage systems, wherein one of said logical storage systems is a global peer-to-peer ring, wherein at least one of the other logical storage systems is a local peer-to-peer ring, wherein said global peer-to-peer ring includes all storage nodes in the geographically distributed storage system connected to each other via a first network, and said local peer-to-peer ring includes storage nodes connected to each other via a second network which forms a part of the first network, and wherein each storage node connected to the second network belongs to both said global peer-to-peer ring and said local peer-to-peer ring, said storage node comprising:

• a plurality of disk drives upon which are formed at least one logical unit which stores data objects;
• and
• a memory which stores global management information concerning said global peer-to-peer ring and local management information concerning said local peer-to-peer ring,
• wherein the global management information includes a second network node table which is used for managing topology information of second networks forming a part of the first network, a metadata table which is used for managing locations of data stored in the storage nodes of the geographically distributed storage system, and a global routing table which is used for managing routing in the global peer-to-peer ring,
• wherein the local management information includes an object management table which is used for managing data objects stored in the storage nodes connected to the second network, a Logical Unit management table which is used for managing logical units in the storage nodes connected to the second network that store the data objects, and a local routing table which is used for managing routing in the local peer-to-peer ring,
• wherein in the global peer-to-peer ring:
• a hash value of a file which is managed by a storage node in is calculated using a file name which indicates a name of the file which is managed by the storage node,
• the storage node managing the file is determined using the calculated hash value of the file which is managed by the storage node,
• the storage node is requested to obtain an Internet Service Provider name corresponding to the file name from the meta data table,
• a hash value of the Internet Service Provider name is calculated,
• the storage node which manages an Internet Service Provider node table of the Internet Service Provider is determined using the calculated hash value of the Internet Service Provider, and
• the storage node uses the Internet Service Provider name to find nodes that constitute the Internet Service Provider using the Internet Service Provider table, and
• wherein in the local peer-to-peer ring:
• a storage node of the local peer-to-peer ring managing the object management table is determined using the calculated hash value of the file which is managed by the storage node, and
• a path name, which is a name of a path used to access a file containing a data object in a local storage of a storage node, is obtained from the object management table, and the data object is requested.