Raid systems and methods for improved data recovery performance

A method comprising:

• distributing a stride of parity data for a parity group across a RAID array consistent with a selected distributed RAID scheme, the RAID array comprising a plurality of storage enclosures each having a plurality of storage drives within;
• determining a set of drives and logical block addresses corresponding to the parity group;
• dividing the set of drives into subsets of drives that are located within each individual storage enclosure of the plurality of storage enclosures;
• issuing a single enclosure-level XOR read (“EnclosureXOR Read”) request to each individual storage enclosure corresponding to the subsets of drives to read enclosure-level intermediate XOR data calculated by each storage enclosure for each subset of drives;
• sending a read request to read a single enclosure-level intermediate XOR data result from the individual storage enclosures, the enclosure-level intermediate XOR data results corresponding to XOR data for the subset of drives within the individual storage enclosures;
• and
• in response to receiving the enclosure-level intermediate XOR data results from all storage drives in the parity group, calculating an array level XOR result by performing an XOR operation on the enclosure-level intermediate XOR data results from the individual storage enclosures.

A computer program product for reducing a number of reads of XOR data in a multi storage enclosure RAID array, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor of a RAID storage controller to cause the RAID storage controller to:

• distribute a stride of parity data for a parity group across a RAID array consistent with a selected distributed RAID scheme, the RAID array comprising a plurality of storage enclosures each having a plurality of storage drives within;
• determine a set of drives and logical block addresses corresponding to the parity group;
• divide the set of drives into subsets of drives that are located within each individual storage enclosure of the plurality of storage enclosures;
• issue a single enclosure-level XOR read (“EnclosureXOR Read”) request to each individual storage enclosure corresponding to the subsets of drives to read enclosure-level intermediate XOR data calculated by each storage enclosure for each subset of drives;
• send a read request to read a single enclosure-level intermediate XOR data result from the individual storage enclosures, the enclosure-level intermediate XOR data results corresponding to XOR data for the subset of drives within the individual storage enclosures;
• and
• in response to receiving the enclosure-level intermediate XOR data results from all storage drives in the parity group, calculate an array level XOR result by performing an XOR operation on the enclosure-level intermediate XOR data results from the individual storage enclosures.