Volume groups storing multiple generations of data in flash memory packages

A storage system comprising:

• a plurality of flash packages, each of which comprises a plurality of flash chips, configured to store data, and
• a storage controller configured to manage a plurality of pages each of which is based on the plurality of flash packages, to maintain a plurality of logical volumes having allocated pages of the plurality of pages, and to receive an access request from a host to the plurality of logical volumes,
• wherein the storage controller is configured to manage a first logical volume of the plurality of logical volumes, to make a second logical volume of the plurality of logical volumes based on the first logical volume, to maintain volume generation information identifying each of the first logical volume and the second logical volume, to manage a first part of the first logical volume where the first part is configured to be an access target of old data and a second part of the second logical volume where the second part is configured to be an access target of new data, and to allocate a page of the plurality of pages to both the first part and the second part,
• wherein the storage controller writes the new data into the page.