US Patent 7475321 Detecting errors in directory entries

In one embodiment, the present invention includes a system, which may be a multiprocessor system having multiple nodes, each with a processor and a cache. The system may include a directory stored in a memory that includes entries having coherency information. At least one of the nodes may be configured to detect an error in an entry of the directory based on a coherency protocol and a state of a status indicator and presence vector of the entry, and without the storage of error correction or parity information in the entry. In some embodiments, the node may correct the error using state information obtained from other nodes.