When a storage drive used as part of a redundant storage system is rebuilt, a drive controller obtains information for the rebuild process from an operating system (OS) specific agent. The information may include a bitmap, which indicates portions of a logical unit being used by the operating system. The bitmap is provided to a controller specific agent, which manipulates the bitmap into a form indicating which physical portions of the storage drive correspond to the portions of the logical unit being used by the operating system. The storage controller uses the bitmap to rebuild those portions of the physical storage drive being used by the operating system prior to rebuilding other portions of the physical storage device.