1. A method comprising: initiating a first store operation to a cache data block stored in a first cache from a first processing node; initiating a first load operation to said cache data block from a second processing node subsequent to initiating said first store operation; assigning a pairwise-shared directory state to a coherence directory entry corresponding to said cache data block in response to initiating said first load operation; initiating a second store operation to said cache data block from said second processing node subsequent to initiating said first load operation; and assigning a migratory directory state to said coherence directory entry in response to initiating said second store operation; wherein said migratory directory state is distinct from a modified directory state; and wherein assigning a migratory directory state further comprises storing an identity of said second processing node.