Patent ID: 7162662

Claim:
A method for updating a qtree stored in a coalesced persistent consistency point image (PCPI) of one or more qtrees, the method comprising the steps of: transitioning from a stable state to an unstable update state as an update procedure commences; transitioning from the unstable update state to a done state in response to the update procedure succeeding; transitioning from the unstable update state to an unstable rollback state in response to the update procedure not succeeding, wherein a rollback procedure is performed to the qtree in the unstable rollback state and wherein the qtree transitions to the done state in response to the rollback procedure succeeding; performing a two step jump ahead procedure from the done state to the stable state wherein a new coalesced base PCPI is exported comprising the qtree; and whereby only a fixed number of PCPIs are consumed in updating the coalesced PCPI.