Patent ID: 6868506

Claim:
In a data processing system with a host and a data storage facility including a cache memory, a standard storage device for receiving write commands and data from the host through the cache memory and a BCV mirror storage device for backing up the standard storage device wherein each of the storage devices comprises a plurality of tracks on a physical disk and the BCV mirror storage device operates either in a first, write-enabled, mirror mode for mirroring the first storage device or in a split mode isolated from the first storage device, a track identification table for each of storage device defining the status of the data in each track of the standard and BCV mirror storage devices, a data recovery program stored on a computer readable medium which when executed by a processor restores data in the standard storage device comprising: A) a program step for attaching the BCV mirror storage device in a read-only state to the standard storage device, B) a program step for identifying tracks to be restored from the BCV mirror storage device to the standard storage device, and C) a program module for initiating concurrent restoration and updating of the data in each track to be restored by performing the steps of: i) copying the data from the identified track in the BCV mirror storage device to the cache memory in response to the information in the track identification table associated with the standard storage device, ii) transferring update data received from the host for the track to the cache memory, and iii) responding to a predetermined track status for a standard storage device track by transferring corresponding data from the cache memory to the standard storage device.