Patent ID: 8516208

Claim:
A data backup method for backing up data from a first storage unit to a second storage unit, the data backup method comprising: dividing a transfer source storage area in the first storage unit in which data to be transferred from the first storage unit to the second storage unit is stored into portions, and providing two transfer destination areas of an equal size, each of the two transfer destination areas being divided into portions; sequentially backing up data in a direction from a beginning address of the divided areas of the transfer source area to an end address thereof in one of the transfer destination areas provided for each divided area of the transfer source storage area, and backing up data in sequence in a direction from the end address of each divided area of the transfer source storage area to the beginning address thereof in the other transfer destination storage area; and completing the backup when the data of all the addresses of the divided areas of the transfer source area is backed up in the divided areas of the transfer destination storage area.