According to one embodiment, a magnetic disk device includes a magnetic disk, a head and a controller. The head writes data to the magnetic disk and reads data from the magnetic disk. The controller once reads the data written to a predetermined recording area according to the number of writes of data to the predetermined recording area of the magnetic disk and rewrites the read data to the predetermined recording area. The controller adjusts an additive value to the number of writes based on the presence or absence of a defect on the recording surface of the magnetic disk.

A method and system of replicating data stored on a storage device where an update is stored in a snapshot. The update includes a copy of at least one portion of the data stored on the storage device. Metadata relating to the update is also stored. The replica is periodically updated by copying the contents of the snapshot into the replica in accordance with the stored metadata. After the replica is updated, the snapshot can be deleted.

A method and system of replicating data stored on a storage device where an update is stored in a snapshot. The update includes a copy of at least one portion of the data stored on the storage device. Metadata relating to the update is also stored. The replica is periodically updated by copying the contents of the snapshot into the replica in accordance with the stored metadata. After the replica is updated, the snapshot can be deleted.

In an approach to automatically reconciling data in HSM without affecting system performance, responsive to migrating a file on a hierarchical storage system from a primary storage to one or more tape drives, one or more file migration records are recorded in a reconcile database. Responsive to the occurrence of a file event on the primary storage, the one or more file migration records in the reconcile database are updated. Responsive to receiving a command to unmount a first mounted tape on one of the one or more tape drives, a reconcile function is performed on the first mounted tape, wherein the reconcile function updates the first mounted tape with the one or more file migration records in the reconcile database.

In an approach to automatically reconciling data in HSM without affecting system performance, responsive to migrating a file on a hierarchical storage system from a primary storage to one or more tape drives, one or more file migration records are recorded in a reconcile database. Responsive to the occurrence of a file event on the primary storage, the one or more file migration records in the reconcile database are updated. Responsive to receiving a command to unmount a first mounted tape on one of the one or more tape drives, a reconcile function is performed on the first mounted tape, wherein the reconcile function updates the first mounted tape with the one or more file migration records in the reconcile database.

A system determines the data stored on a portion of magnetic media by obtaining an image that represents the magnetic state of the portion of magnetic media using a magneto-optic image sensor. In an example, the image sensor is connected to a mechanism that moves over the portion of magnetic media, and the system takes a plurality of images which are stitched together into a composite image of the state of the portion of magnetic media. The system analyzes the image to identify regions that contain data, extracts the encoded data from the regions. The encoded data is decoded in accordance with an encoding scheme used by the portion of magnetic media. In some examples, a file structure is applied to the data and data files are recovered from the image. In various examples, the portion of magnetic media can be hard disk media, floppy disk media, or magnetic tape.

A data storage device is disclosed comprising a head actuated over a magnetic media comprising a plurality of data tracks, wherein each data track comprises a plurality of data sectors. A plurality of access commands are stored in a command queue, and an access command is selected from the command queue. When the selected access command is a write command to a target data track and at least part of a first data track proximate the target data track needs to be refreshed, a refresh read command is executed to read data from at least part of the first data track prior to executing the write command to the target data track.

In an approach to automatically reconciling data in HSM without affecting system performance, responsive to migrating a file on a hierarchical storage system from a primary storage to one or more tape drives, one or more file migration records are recorded in a reconcile database. Responsive to the occurrence of a file event on the primary storage, the one or more file migration records in the reconcile database are updated. Responsive to receiving a command to unmount a first mounted tape on one of the one or more tape drives, a reconcile function is performed on the first mounted tape, wherein the reconcile function updates the first mounted tape with the one or more file migration records in the reconcile database.

In an approach to automatically reconciling data in HSM without affecting system performance, responsive to migrating a file on a hierarchical storage system from a primary storage to one or more tape drives, one or more file migration records are recorded in a reconcile database. Responsive to the occurrence of a file event on the primary storage, the one or more file migration records in the reconcile database are updated. Responsive to receiving a command to unmount a first mounted tape on one of the one or more tape drives, a reconcile function is performed on the first mounted tape, wherein the reconcile function updates the first mounted tape with the one or more file migration records in the reconcile database.

According to one embodiment, a magnetic disk device includes a magnetic disk, a head and a controller. The head writes data to the magnetic disk and reads data from the magnetic disk. The controller once reads the data written to a predetermined recording area according to the number of writes of data to the predetermined recording area of the magnetic disk and rewrites the read data to the predetermined recording area. The controller adjusts an additive value to the number of writes based on the presence or absence of a defect on the recording surface of the magnetic disk.