Patent ID: 7328226
Filing Date: 2008-02-05
Classification: G06F,Y10S

Abstract:
1. A method for coordinating access to a storage volume between a plurality of hosts, wherein each host is associated with one of a plurality of logs, the method comprising: a host of the plurality of hosts receiving from an application a write request to write application data to a region of the storage volume; the host requesting permission from a coordinator to write the application data to the region of the storage volume; the host storing the application data to an associated one of the plurality of logs; the host initiating a read of an old version of data in the region of the storage volume; the host receiving from the coordinator a response granting permission to write the application data to the region of the storage volume, wherein the response indicates that the old version of data in the region of the storage volume should be relocated to a COW (Copy On Write) snapshot volume; the host writing the old version of data in the region of the storage volume to the COW snapshot volume in response to the indication that the old version of data in the region of the storage volume should be relocated; the host providing a signal to the application indicating completion of the write request, wherein the signal is provided to the application prior to writing the application data to the region of the storage volume and subsequent to both storing the application data to the associated one of the plurality of logs and receiving the response from the coordinator; and the host writing the application data to the region of the storage volume after providing the signal to the application and after writing the old version of data in the region of the storage volume to the COW snapshot volume.