Storage system

A storage system comprising:

• a storage device;
• and
• a processor configured to process data input to and output from the storage device, wherein
• the processor is further configured to:
• form a page capable of storing a plurality of pieces of data in a logical storage area configured based on a physical storage area of the storage device;
• provide a volume and input/output data related to data input/output with respect to the volume to/from a page of the logical storage area;
• map the volume to data of the logical storage area;
• include a plurality of the volumes that can share data of the logical storage area;
• perform garbage collection processing of deleting data which is not referred to from any of the plurality of volumes as invalid data, moving data which is referred to from any of the plurality of volumes to another page, and releasing a storage area of a page on which the data is deleted and the data is moved;
• set a page mapped from the same volume for all stored data to be excluded from the garbage collection processing;
• and
• when the one volume to which data of a page set to be excluded from the garbage collection processing is mapped is deleted, delete the data and release a storage area of a page.