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.