An apparatus for providing storage control in a network of storage
controllers is disclosed. The apparatus includes an owner storage
controller; an I/O performing component, an ownership assignment
component, a lock manager and a messaging component. The ownership
assignment component assigns ownership of metadata for data to an owner
storage controller. The lock manager controls the locking of metadata
during I/O. The messaging component passes messages among storage
controllers to request metadata state, to grant locks, to request release
of locks, and to signal lock release. The I/O is performed on data whose
metadata is owned by an owner storage controller, subject to compliance
with metadata lock protocols controlled by the owner storage controller,
and any copy of the data held from time to time is maintained in a
coherency relation with the data.