Patent ID: 6721902
Filing Date: 2004-04-13
Classification: G06F

Abstract:
A method employed by a computer-based entity for backing up a computer-readable object stored on a first logical device unit, the method comprising:obtaining by the computer-based entity a lock on a second logical device unit; when a mirror for the object has not yet been created on the second logical device, creating a mirror for the object on the second logical device unit implemented on one or more mass storage devices; when the object and the mirror for the object are split, resyncing the object with the mirror for the object; splitting the object and the mirror for the object so that the mirror becomes a backup copy of the object and so that I/O requests directed to the object are not automatically directed to the mirror; when the object is determined to need to be restored from the mirror, retrieving lock information from the second logical device unit, including an indication of whether or not a lock is currently held on the second logical device unit, and, when a lock is currently held on the second logical device unit, an indication of the owner of the lock; when, as determined from the indication of the owner of the lock, the computer-based entity holds a lock on the second logical device unit, using the mirror to create, replace, or update the object on the first logical device.