Patent ID: 7647463

Claim:
An apparatus to detect mismatches in a mirror volume, the apparatus comprising: a receive module configured to receive at a secondary storage system a start indicator from a primary storage system, the start indicator comprising an indication of a location of a first block to be modified on a track of a data storage device in the secondary storage system, the first block of the secondary storage system corresponding to an identically located first block of at least one modified record on a track of a data storage device in the primary storage system, wherein the tracks on the primary and secondary storage systems each comprise irregular count key data (“CKD”) tracks; a compare module configured to compare the first block location indicated by the start indicator with block locations listed in track metadata, wherein the track metadata describes lengths and locations of user records on the irregular CKD tracks of the secondary storage system; and an alert module configured to generate an alert in response to the first block indicated by the start indicator not aligning with a beginning block of a record on the secondary storage system, as indicated in the track metadata.