Patent ID: 8886869

Claim:
A storage system, which is coupled to a host apparatus, the storage system comprising: multiple flash packages each comprising multiple flash memory chips and a package controller for controlling storage areas of the multiple flash memory chips; and a storage controller that uses the storage areas of the multiple flash memory packages to provide a first LU (Logical Unit) and a second LU to the host apparatus, each of the first LU and the second LU corresponding to a plurality of the multiple flash packages, and each of the plurality of the multiple flash packages corresponding to a plurality of LUs, wherein when managing the first LU as a backup target and the second LU as a non-backup target, the package controller configured to: upon receiving an update data write request with respect to a first logical storage area corresponding to the first LU, manage a first physical storage area allocated to the first logical storage area as a backup storage area in a state where pre-update data is maintained, newly allocate a second physical storage area to the first logical storage area, write the update data to the second physical storage area, and determine a snap shot flag corresponding to the first LU is ON or OFF, upon receiving an update data write request with respect to a second logical storage area corresponding to the second LU, manage a third physical storage area allocated to the second logical storage area as an invalid storage area, write the update data to a fourth physical storage area newly allocated to the second logical storage area, and determine a snap shot flag corresponding to the second LU is ON or OFF, use the first physical storage area that is managed as the backup storage area to provide backup data for the first LU, and delete pre-update data stored in the third physical storage area that is managed as the invalid storage area, and wherein when the snap shot flag corresponding to the first or second LU is ON and a latest generation of snap shot data does not exist, add an old physical page to a snap shot generation list, and wherein when the snap shot flag corresponding to the first or second LU is OFF, or when the snap shot flag corresponding to the first or second LU is ON and a latest generation of snap shot data exists, set a status of the old physical page to invalid.