Patent ID: 8527463
Filing Date: 2013-09-03
Classification: G06F,H04L,Y10S

Abstract:
1. A method of maintaining a copy of at least one data volume in a computer system for at least one point in time, comprising: initiating creation of a first snapshot of a base volume; establishing a first repository for the first snapshot of the base volume; creating a modified region map, the modified region map including a respective bit representing each region of the base volume, each bit indicating whether any data in a respective region has changed; monitoring the base volume for write operations thereto; identifying a write operation to a first region of the base volume; determining whether the modified region map indicates that data has changed in the first region since initiation of the first snapshot; prior to a write operation to the first region of the base volume, copying the first region of the base volume to the first repository in response to an indication by the modified region map that data in the first region has not been changed since initiation of the first snapshot; and upon reinitialization of a system maintaining the first repository, rebuilding the modified region map to determine if bits should be set corresponding to regions for which a write operation was completed prior to interruption of the system.