Computer system and computer system management method for adding an unused real volume to a pool

A computer system, comprising:

• multiple storage control apparatuses configured to create at least one virtual logical volume;
• at least one host computer configured to use the virtual logical volume;
• and
• at least one management computer for managing the respective storage control apparatuses and the host computer,
• wherein each of the storage control apparatuses is configured to allocate a real storage area of a real volume inside a pool to the virtual logical volume in response to a write access from the host computer, and to store write data received from the host computer in the allocated real storage area,
• wherein the management computer comprises:
• a microprocessor configured to read and execute a prescribed computer program;
• a memory for storing the prescribed computer program;
• and
• a communication interface part for communicating with the respective storage control apparatuses and the host computer,
• wherein the microprocessor, by reading and executing the prescribed computer program, is configured to:
• acquire a utilization status of each of the pools;
• determine, based on the acquired utilization status of each of the pools, whether or not there exists a prescribed pool that requires pool size expansion;
• when the prescribed pool is detected, select, based on a prescribed selection criterion, a volume addition method for adding an unused real volume to the prescribed pool;
• and
• expand a pool size of the prescribed pool in accordance with the selected method.