Data mirror volume verification

For volume verification, an apparatus is disclosed. The apparatus includes a data mirror that generates volume pairs of first and second volumes by mirroring track data from first volumes stored by a first device to second volumes as mirrored track data stored by a second device. The apparatus includes an activity monitor that monitors update activities for volume pairs and identifies volume pairs having substantial residual counts of update activities as indicated by a pre-determined residual count threshold. The apparatus includes a data verifier that selects one or more identified volume pairs for evaluation, compares the track data in the first volume to the mirrored track data in the second volume, and if a match discrepancy is determined, then re-copies the track data from the first volume to the second volume so as to correct and repair the mirrored track data in the second volume.