Patent ID: 7743208

Claim:
A storage apparatus used in a distributed storage system, comprising: a file memory to store data corresponding to identifiers of an allocated area in an identifier space; a first memory to store a basis position of the allocated area in the identifier space; a second memory to store a weight of the storage apparatus as a performance degree, the weight being calculated by at least one of calculation ability and circuit speed of the storage apparatus; a first decision unit configured to decide a space width to divisionally allocate the identifier space with another storage apparatus by using the weight and a weight of the another storage apparatus, the another storage apparatus allocating a neighboring area of the allocated area in the identifier space; and a second decision unit configured to decide the allocated area of an area between the basis position and a basis position of the neighboring area in the identifier space by using the space width, wherein said first decision unit calculates a sum of the weight of the storage apparatus and the weight of the another storage apparatus, divides the weight of the storage apparatus by the sum, and sets the division result as the space width; and wherein said second decision unit multiplies a value of the basis position of the storage apparatus with a subtraction value of the space width from one as a first multiplication value, multiplies a value of the basis position of another storage apparatus with the space width as a second multiplication value, calculates a sum of the first multiplication value and the second multiplication value, and sets an area between a position of the sum and the basis position of the storage apparatus in the identifier space as the allocated area.