Storage apparatus and its control method

A control method for a storage apparatus including a plurality of storage devices for managing storage areas provided by the respective storage devices as one pool, associating logical devices, which are cut out from part of the pool, with logical units, and providing the logical units as storage areas to a host system,

• the storage apparatus including:
• a channel control unit that transmits and receives a command and data to and from the host system;
• and
• a plurality of command processing units, each of which processes the command from the host system,
• wherein each of the command processing units having ownership of a logical device is set to that logical device in advance with respect to each logical device and the command, which is targeted at the logical unit associated with the logical device, from the host system is executed by the command processing unit having the ownership of the logical unit;
• wherein a plurality of the logical units are managed as one group and one logical unit in the group is defined as a logical unit representative of the group;
• and
• wherein a format of the command targeted at the logical unit representative of the group is different from a format of the command targeted at the logical unit other than the above-mentioned logical unit in the group;
• the control method comprising:
• a first step executed by the channel control unit analyzing the format of the command issued from the host system;
• and
• a second step executed, when on the basis of a result of the analysis the logical unit targeted by the command is the logical unit other than the logical unit representative of the logical unit in the group, by the channel control unit transferring the relevant command to the command processing unit having the ownership of the logical device associated with the logical unit targeted by the command.