Patent ID: 8255739

Claim:
A computer-implemented method for restoring data consistency in a RAID array in a degraded mode upon failover from a primary storage node of a storage cluster to a secondary storage node of the storage cluster, the method comprising: receiving a write input/output (“I/O”) operation at the primary storage node; upon receiving the write I/O operation when the RAID array is in a degraded mode, reading a missing data strip from the RAID array corresponding to the stripe targeted by the write I/O operation; sending the missing data strip to the secondary storage node; taking ownership of the RAID array upon failure of the primary storage node; reading the missing data strip from an outstanding strip log, wherein a size of the strip log is set to be at least a size of an outstanding input/output (“I/O”) log supported by the underlying RAID array; and writing the missing data strip to the RAID array, wherein writing the missing data strip to the RAID array transforms the stripe on the RAID array containing the data strip from an inconsistent state to a consistent state, wherein the primary storage node processes all write I/O operations for the RAID array in the storage cluster, and wherein both the primary storage node and the secondary storage node process read I/O operations for the RAID array in the storage cluster.