Patent ID: 8473700

Claim:
A computer program product for managing Input/Output (I/O) requests to a storage device, the computer program product comprising a computer readable storage medium having computer readable program code embodied therein that executes to perform operations, the operations comprising: receiving a write request having write data for a logical address in the storage device; determining whether preserve mode is enabled; locating a first entry in a volume control table for the logical address indicating a version number of the data in the storage device for the logical address and a first physical location in the storage device having the data for the logical address; writing the write data to a second physical location in the storage device; adding a second entry to the volume control table for the logical address to write in response to determining that the preserve mode is enabled; in response to determining that the preserve mode is enabled, updating the volume control table to have one of the first and second entry for the logical address point to the second physical location and have the version number indicate a current version and to have the first or second entry not indicating the current version to indicate the first physical location and the version number indicate a previous version; determining at least one additional entry in the volume control table for the logical address to update in addition to the first and second entries; and reducing a version number indicated in the at least one additional entry to indicate a lower version number than the version number currently indicated in the at least one additionally entry.