Storage control apparatus and storage control method for recovering data in a failed storage device of a RAID sysytem

A storage control apparatus, comprising:

• a plurality of storage units each comprising a plurality of storage devices;
• power supply devices which have a function of turning ON and OFF supply of power to each of said plurality of storage units individually;
• and
• a control device which can communicate with a management device for inputting commands of various types,
• wherein said control device:
• receives a RAID (Redundant Array of Independent Disks) setting command from said management device which designates two or more storage devices within said plurality of storage units, and sets said two or more storage devices which have been designated as a single RAID group;
• receives a spare setting command from said management device which designates at least one storage device within said plurality of storage units, and sets said at least one storage device which has been designated as a spare device for said single RAID group;
• performs unit power supply control by controlling said power supply devices so as to turn the power supply to each of said storage units ON and OFF individually;
• controls said management device when said RAID setting command is inputted, so that said two or more storage devices which can be designated by said RAID setting command as said single RAID group are limited to being only said two or more storage devices which are present in a same storage unit;
• receives a function setting command from said management device which designates whether or not said unit power supply control is to be valid, and sets said unit power supply control to be valid or invalid according thereto;
• and
• when said individual turning ON and OFF function is changed over from invalid to valid, checks whether or not two or more of the storage devices which are included in said single RAID group are present as dispersed over different storage units, and if the result of this check is YES, notifies said management device of the necessity of re-setting that RAID group,
• wherein when said individual turning ON and OFF function has been changed over from invalid to valid, said control device further checks whether or not said copy-back is set as said recovery processing, and if a result of checking is YES, said control device notifies said management device of a necessity of changing from copy-back to copy-backless.