Storage system and information processing apparatus

An information processing apparatus that is connected to a plurality of storage nodes, each including a plurality of data regions and a parity region corresponding to the plurality of data regions, the information processing apparatus comprising:

• one or more processors configured to perform a procedure including:
• replicating a plurality of data elements respectively stored in the plurality of data regions of one of the plurality of storage nodes, and storing replicated data elements respectively in the plurality of data regions of each of the other storage nodes,
• generating a parity corresponding to the data elements respectively stored in the plurality of data regions, and storing the parity in the parity region, for each of the storage nodes, and
• selecting, for each of the storage nodes, one or more data regions that hold data elements, from among the plurality of data regions, based on a calculation using a node number which identifies said each storage node and releasing one or more non-selected data regions so as to reduce a multiplicity of the data elements respectively stored in the plurality of data regions of each of the plurality of storage nodes,
• wherein node numbers respectively identifying the plurality of storage nodes are in ascending order;
• and
• wherein the selecting includes selecting a digit from a bit string indicating the node number in order from a most significant digit of the bit string to a least significant digit of the bit string based on a count of the selecting of a digit and selecting the one or more data regions based on the calculation using a value of the digit selected.

A non-transitory computer-readable storage medium storing a program that causes an information processing apparatus, which is connected to a plurality of storage nodes, each including a plurality of data regions and a parity region corresponding to the plurality of data regions, to perform a procedure comprising:

• replicating a plurality of data elements respectively stored in the plurality of data regions of one of the plurality of storage nodes, and storing replicated data elements respectively in the plurality of data regions of each of the other storage nodes;
• generating a parity corresponding to the data elements respectively stored in the plurality of data regions, and storing the parity in the parity region, for each of the storage nodes;
• and
• selecting, for each of the storage nodes, one or more data regions that hold data elements, from among the plurality of data regions, based on a calculation using a node number which identifies said each storage node and releasing one or more non-selected data regions so as to reduce a multiplicity of the data elements respectively stored in the plurality of data regions of each of the plurality of storage nodes,
• wherein node numbers respectively identifying the plurality of storage nodes are in ascending order;
• and
• wherein the selecting includes selecting a digit from a bit string indicating the node number in order from a most significant digit of the bit string to a least significant digit of the bit string based on a count of the selecting of a digit and selecting the one or more data regions based on the calculation using a value of the digit selected.