Cost reduction schema for advanced raid algorithms

Abstract

A signal bearing medium tangibly embodying a program of machine-readable instructions executable by a processor to perform operations to read information stored in a storage system. The storage system includes a controller coupled to a plurality of type I performance class disk drives and at least one type II performance class backup disk drive. The operations include executing a first read request for a first set of information from a first type I performance class disk drive and executing a second read request for the first set of information from a first type II performance class backup disk drive in response to an occurrence of a first read error associated with the execution of the first read request.

1 . A method for reading information stored in a double mirror storage system, the double mirror storage system including a controller coupled to a plurality of type I performance class disk drives and at least one type II performance class backup disk drive, wherein the type I performance class disk drives contain data blocks and parity blocks for the data blocks and wherein the type II performance class disk drives contain redundant data blocks and redundant parity blocks, the method comprising:
 executing a first read request for a first set of information from a first type I performance class disk drive, wherein the information constitutes segments of at least one of the data block and the parity block;   determining a first read error associated with the execution of the first read request; and   executing a second read request for the first set of information from a first type II performance class backup disk drive wherein the controller minimizes the use of the first type II performance class drive and maximizes the use of the first type I performance drive.   
     
     
         2 . The method of  claim 1 , further comprising:
 executing a third read request for the first set of information from a second type II performance class backup disk drive in response to the occurrence of the first read error associated with the execution of the first read request.   
     
     
         3 . The method of  claim 2 , wherein the first type I performance class disk drive comprises a server class disk drive and the first type II performance class backup disk drive comprises a desktop class disk drive. 
     
     
         4 . The method of  claim 2 , wherein the first type I performance class disk drive comprises a fiber channel disk drive and the first type II performance class backup disk drive comprises an ATA disk drive. 
     
     
         5 . The method of  claim 1 , further comprising:
 executing a third read request for a second set of information from a second type I performance class disk drive; and   executing a fourth read request for the second set of information from a second type II performance class backup disk drive in response to an occurrence of a second read error associated with the execution of the third read request.   
     
     
         6 . The method of  claim 5 , wherein the second set of information constitute segments of at least one of a data block and a parity block. 
     
     
         7 . A method for reading information stored in a double mirror storage system, the double mirror storage system including a controller coupled to a plurality of type I performance class disk drives and at least one type II performance class backup disk drive, wherein the type I performance class disk drives contain data blocks and parity blocks for the data blocks and wherein the type II performance class disk drives contain redundant data blocks and redundant parity blocks the method comprising:
 executing a first read request for a first set of information from a first type I performance class disk drive; and   executing a second read request for the first set of information from a first type II performance class backup disk drive in response to an occurrence of a first read error associated with the execution of the first read request wherein the controller minimizes the use of the first type II performance class drive and maximizes the use of the first type I performance drive.   
     
     
         8 . The method of  claim 7 , further comprising:
 executing a third read request for the first set of information from a second type II performance class backup disk drive in response to the occurrence of the first read error associated with the execution of the first read request.   
     
     
         9 . The computer usable medium of  claim 2 , wherein the first type I performance class disk drive comprises a server class disk drive and the first type II performance class backup disk drive comprises a desktop class disk drive. 
     
     
         10 . The method of  claim 9 , wherein the first type I performance class disk drive comprises a fiber channel disk drive and the first type II performance class backup disk drive comprises an ATA disk drive. 
     
     
         11 . The method of  claim 7 , further comprising:
 executing a third read request for a second set of information from a second type I performance class disk drive; and   executing a fourth read request for the second set of information from a second type II performance class backup disk drive in response to an occurrence of a second read error associated with the execution of the third read request.   
     
     
         12 . The method of  claim 11 , wherein the first set of information and the second set of information constitute segments of at least one of a data block and a parity block.