System and methods for RAID writing and asynchronous parity computation

A computer storage management method for managing a first plurality of computer storage units operative to store data each including at least a second plurality of corresponding data portions, the method comprising:

• managing writing operations and asynchronously computing at least one parity, including, responsive to occurrence of at least one write operation in which an incoming value is to be written into a location in an individual computer storage unit from among the computer storage units,
• depositing said incoming value in said individual storage unit, thereby to define an individual data portion stored therewithin, and in a pre-parity storage area, and
• computing and storing a parity combining the incoming value with the values of those data portions, in the computer storage units other than said individual computer storage unit, which correspond to said individual data portion;
• and
• recovering lost data including determining whether at least one parity of at least one data portion within said lost data is not current and, for at least one non-current parity, using information stored in the pre-parity storage area to generate, after said lost data has been lost, a current parity to replace said non-current parity and using said current parity to recover said lost data.

A computer program product, comprising a non-transitory computer usable medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed to implement a computer storage management method for managing a first plurality of computer storage units operative to store data each including at least a second plurality of corresponding data portions, the method comprising:

• managing writing operations and asynchronously computing at least one parity, including, responsive to occurrence of at least one write operation in which an incoming value is to be written into an individual computer storage unit from among the computer storage units,
• depositing said incoming value in said individual storage unit, thereby to define an individual data portion stored therewithin, and in a pre-parity storage area, and
• computing and storing a parity combining the incoming value with the values of those data portions, in the computer storage units other than said individual computer storage unit, which correspond to said individual data portion;
• and
• recovering lost data including determining whether at least one parity of at least one data portion within said lost data is not current and, for at least one non-current parity, using information stored in the pre-parity storage area to generate, after said lost data has been lost, a current parity to replace said non-current parity and using said current parity to recover said lost data.