Storage system

A storage system comprising:

• a central processing unit;
• a main memory including a program area and a working area of the central processing unit;
• first management information that associates a hash value of received data with an address in a volume;
• and
• an I/O processing package, wherein
• the I/O processing package includes
• an I/O processor and
• an I/O memory including a program area and a working area of the I/O processor,
• the central processing unit controls read processing and write processing of user data,
• the I/O processor executes protocol processing,
• the I/O processor executes at least a part of search processing of an address associated with a hash value of first received data in the first management information, and
• the central processing unit controls execution of deduplication processing of the first received data based on data of an address associated with the hash value of the first received data.