Patent ID: 6978280

Claim:
A method for backing up a computer-readable object stored on a first logical unit of a mass-storage device, the method comprising: when the object is not currently mirrored to a mass storage device, creating a mirror for the object on a second logical unit of the mass-storage device; 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 for the object becomes a backup copy of the object and so that I/O requests directed to the object are not automatically directed to the mirror for the object; retrieving a first instance of a current timestamp from associated, by the mass-storage device with the second logical unit and saving it as a saved timestamp; updating, by the mass-storage device, the current timestamp associated with the second logical unit upon executing any I/O operation directed to the second logical unit that alters data stored on the second logical unit; when the object is determined to need to be restored from the backup copy, retrieving a second instance of the current timestamp associated with the second logical unit; comparing the retrieved second instance of the current timestamp associated with the second logical unit to the saved timestamp; and when the second instance of the current timestamp associated with the second logical unit is equal to the saved timestamp, copying the backup copy to the first logical unit.