Relocation manner of the data in the data storage system, access manner and data storage system null of the data which is stored in that system

摘要

In a disk array system, such as a RAID system, when disks are added thereto, this invention rearranges data without requiring a back-up of the stored data. When new data storage units are added into a RAID system in which each data storage unit is a row and an address range of the data storage unit is a column, a new striping rule dependant on the number of data storage units in the system, inclusive of newly added unit, is determined. Data are rearranged in the storage areas according to the new striping rule. In rearranging one row according to the new striping rule, the data involved in the transfer to one row from the other row, continues to be stored as a place holder block. Data that has been rearranged is accessed according to the new striping rule which data that has not been rearranged is accessed according to the old striping rule.