Memory system and method for controlling memory system

A control method of a memory system in which any of a plurality of physical blocks in a non-volatile memory is connected to a plurality of channels, the control method comprising:

• constructing a plurality of logical blocks;
• and
• reading or writing data from or into any of the plurality of logical blocks constructed,
• wherein the logical blocks are management units in which any of the physical blocks is grouped across the plurality of channels, and
• the constructing includes:
• specifying a first number of defective blocks among the plurality of physical blocks;
• specifying a second number of shortfall defective blocks with respect to a target number of defective blocks depending on the first number;
• preparing second number of pseudo defective blocks;
• and
• constructing the plurality of logical blocks so that the first number of defective blocks and the second number of pseudo defective blocks are distributed into the plurality of logical blocks.