Each of multiple computers in a cluster of computers negotiates access to
locations in a common storage system. Each of the computers (coupled
together via a network) in the cluster includes a transaction manager
application to coordinate access to shared storage locations (such as a
volume or portions thereof) in the storage system. The transaction
managers at each of the multiple computers utilize a unified address
space that maps locations in the storage system to corresponding access
properties maintained by respective transaction managers in the
computers. The access properties derived from use of the unified address
space indicate an access status of the regions or locations in the shared
storage system. If necessary, the computers in a cluster communicate with
each other to negotiate access to the shared storage. Also, the computers
in a cluster communicate so that current access properties maintained in
each computer are consistent.