| 摘要 |
A system and method are provided that is used by software implemented Redundancy Array of Inexpensive Disk (RAID) arrays to achieve adequate performance and reliability, as well as to improve performance or low cost hardware Raids. The enhancements to the basic RAID implementation speeds up recovery time for software RAIDS. A method is provided for storing data in an array of storage devices. A plurality of block locations on the storage devices are logically arranged as a parity group wherein a parity block stored in a block location as part of a parity group is logically derived from the combination of data blocks stored in the parity group, and each block in a parity group is stored on a different storage device. A plurality of parity groups are grouped into a parity group set. A request is received to write a new data block location on a storage device. The old data block stored at the block location is read. The new data block is written to the block location. When the parity set is in an unmodified state prior to the current write, an indicator is written to the storage device that the parity group set is in a modified state. In a preferred embodiment, this enhancement uses a bit map stored on disk, called Parity Group Set, (PGS) bit map, to mark inconsistent parity groups, replacing the Non-Volatile Random Access Memory, (NVRAM) used for similar purposes by hardware RAIDs. Further enhancements optimized sequential input/output, (I/O) data stream. |
