System and method for virtualizing network storages into a single file system view

A method for virtualizing a plurality of network storages connected to a network into a virtualized network storage system which can be accessed from a client as a single network storage, the method comprising steps of:

• predetermining a group map function which correlates a file to only one file group based on a hash function of a file identifier of the file by using a file inode number I as a search key and a hash value given by the hash function G=Hash (I) which constitutes a file group identifier G;
• performing said group map function for at least said file;
• creating a file group allocation table which records mutual correlation between each of a plurality of file groups and a destination network storage to store files belonging to a corresponding one of the file groups according to said group map function;
• storing each of the grouped files into said destination network storage, respectively;
• periodically issuing an available remaining capacity acquisition request to each destination network storage;
• when the available remaining capacity of a first destination network storage in said virtualized network storage system drops below a first threshold value, selecting only one file group from among file groups stored in said first destination network storage and said file group as a file group to be moved;
• selecting a second destination network storage other than said first destination network storage as a movement destination network storage;
• moving files of the selected file group to the second destination network storage;
• updating an old mutual correlation between the selected file group and the first destination network storage into a new correlation between the selected file group and the second destination network storage in said file group allocation table;
• and
• repeating the steps of selecting, moving and updating until the remaining available capacity of the first destination network storage exceeds a second threshold value.

A method for virtualizing a plurality of network storages connected to a network into a virtualized network storage system which can be accessed from a client as a single network storage, the method comprising steps of:

• predetermining a group map function which correlates a file to only one file group based on a hash function of a file identifier of the file by using a file inode number I as a search key and a hash value given by the hash function G=Hash (I) which constitutes a file group identifier G;
• performing said group map function for at least said file;
• creating a file group allocation table which records mutual correlation between each of a plurality of file groups and a destination network storage to store files belonging to a corresponding one of the file groups according to said group map function;
• storing each of the grouped files into said destination network storage, respectively;
• periodically issuing an available remaining capacity acquisition request to each destination network storage;
• when a differential between a maximum available remaining capacity among respective available remaining capacities in respective destination network storages and a minimum available remaining capacity in a first destination network storage of said virtualized network storage system exceeds a first threshold value, selecting only one file group from among file groups stored in said first destination network storage;
• selecting a second destination network storage other than said first destination network storage as a movement destination network storage;
• moving files of the selected file group to the second destination network storage;
• updating an old mutual correlation between the selected file group and the first destination network storage into a new correlation between the selected file group and the second destination network storage in said file group allocation table;
• and
• repeating the steps of selecting, moving and updating until the differential of the remaining available capacities of said first destination network storage drops below a second threshold value.