Apparatus, system, and method for differential backup using snapshot on-write data

A device for backing up data, comprising:

• a data storage device comprising an active data storage volume comprising a data set and a backup data storage volume;
• an on-write data structure configured to receive a write record for a write to a data block in the data set, the write record comprising a data block identifier;
• a snapshot module configured to record the write record for the write to the data block of the data set in the on-write data structure;
• a backup module configured to copy the data set to the backup data storage device and copy a first differential time stamp and the data block indicated by the data block identifier of the recorded write record to the backup data storage device as a first differential data set backup wherein the data set remains accessible on the active data storage device during each copy;
• a restore module configured to recover the data set responsive to receiving a restore command comprising a data set identifier and a target time value, wherein if the data set identifier indicates the data set, the restore module is further configured to copy the full data set backup to the active data storage device and if the target time value is subsequent to or equivalent to the first differential time stamp to copy each data block of the first differential data set backup to the active data storage device overlaying the corresponding data block of the full data set backup.

A system to backup data, the system comprising:

• an active data storage device comprising a data set;
• a backup data storage device;
• an on-write data structure configured to receive a write record for a write to a data block in the data set, the write record comprising a data block identifier;
• a snapshot module configured to record the write record for the write to the data block of the data set in the on-write data structure;
• and
• a backup module configured to copy the data set to the backup data storage device as a full data set backup and copy a first differential time stamp and the data block indicated by the data block identifier of the recorded write record to the backup data storage device as a first differential data set backup wherein the data set remains accessible on the active data storage device while copied.

A signal bearing medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations to backup data, the operations comprising:

• maintaining the on-write data structure comprising the write record for a write to a data block of the data set of an active data storage device, the write record comprising a data block identifier;
• copying the data set to a backup data storage device as a full data set backup wherein the data set remains accessible on the active data storage device;
• recording the write record for the write to the data block of the data set in the on-write data structure;
• and
• copying the block indicated by the data block identifier of the recorded write record to the backup data storage device as a first differential data set backup, the first differential data set backup further comprising a first differential time stamp.

A method for backing up data, the method comprising:

• maintaining the on-write data structure comprising the write record for a write to a data block of the data set of an active data storage device, the write record comprising a data block identifier;
• copying the data set to a backup data storage device as a full data set backup wherein the data set remains accessible on the active data storage device;
• recording the write record for the write to the data block of the data set in the on-write data structure;
• copying the block indicated by the data block identifier of the recorded write record to the backup data storage device as a first differential data set backup, the first differential data set backup further comprising a first differential time stamp;
• receiving a restore command comprising a data set identifier and a target time value;
• copying the full data set backup to a target data storage device;
• and
• copying the data block of the first differential data set backup to the target data storage device overlaying the corresponding data block of the full data set backup responsive to the restore command and if the target time value is subsequent to or equal to the first differential time stamp.

An apparatus to back up data, the apparatus comprising:

• means for determining a data block size for a write record of an on-write data structure;
• means for maintaining the on-write data structure comprising the write record for a write to a data block of the data set of an active data storage device, the write record comprising a data block identifier;
• means for copying the data set to a backup data storage device as a full data set backup wherein the data set remains accessible on the active data storage device;
• means for recording the write record for the write to the data block of the data set in the on-write data structure;
• and
• means for copying the block indicated by the data block identifier of the recorded write record to the backup data storage device as a first differential data set backup, the first differential data set backup further comprising a first differential time stamp.