Incomplete write protection for disk array

Abstract

The embodiments of the invention provide methods of protecting data blocks while writing to a storage array, wherein storage units in the storage array include write logs. The data protection level of the write logs is equal to or greater than the data protection level of the storage units. Moreover, the write logs have metadata describing contents of the write logs, wherein the metadata include a sequence number identifying the age of the metadata. Each of the data blocks is a member of a parity group having addressable data blocks and first parity blocks. The addressable data blocks have at least one host data block and at least one associated data block.

1 . A method of protecting data blocks while writing to a storage array, wherein storage units in said storage away comprise write logs, wherein each of said data blocks is a member of a parity group comprising addressable data blocks and first parity blocks, and wherein said addressable data blocks comprise at least one host data block and at least one associated data block, said method comprising:
 reading at least one of said associated data block and said first parity blocks from said parity group,   writing said associated data block to said write logs,   creating second parity blocks from said associated data block,   writing said second parity blocks to said write logs,   creating updated first parity blocks from an updated host data block,   writing said updated host data block and said updated first parity blocks to said storage units   clearing said write logs,   issuing a write complete indication,   adding an error-correcting code to said address pointer;   prior to said creating of said updated first parity blocks, setting an address pointer for said write logs in a non-volatile memory such that said address pointer indicates a location of said write logs; and   prior to said clearing of said write logs, clearing said address pointer,   wherein said setting of said address pointer comprises setting said address pointer in battery-backed random access memory on a motherboard,   wherein said writing of said associated data block to said write logs comprises:
 writing a first associated data block to a write log on a storage unit comprising said host data block; and 
 writing a second associated data block to a write log on a storage unit comprising a first redundancy block of said first parity blocks, 
   wherein said writing of said second parity blocks to said write logs comprises:
 writing a first block of said second parity blocks to a write log on a storage unit comprising a second redundancy block of said first parity blocks; and 
 writing a second block of said second parity blocks to a write log on a storage unit comprising a third redundancy block of said first parity blocks, 
   wherein a data protection level of said write logs is one of equal to and greater than a data protection level of said storage units, and   wherein said write logs comprise metadata describing contents of said write logs, and   
       wherein said metadata comprises a sequence number identifying an age of said metadata. 
     
     
         2 - 20 . (canceled)