Patent ID: 7257675
Filing Date: 2007-08-14
Classification: G06F

Abstract:
1. A disk array device having a snapshot simulation function, comprising: bitmap information storage means for storing a bitmap indicating presence or absence of updating for each management unit of a logical volume; bitmap information updating means for updating the bitmap of said bitmap information storage means; updating range determination means for determining which management units of the logical volume cover a range of specified update data and giving notice of bits on the bitmap of said bitmap information storage means corresponding to the management units; snapshot simulation function management means for turning on a valid flag of the snapshot simulation function according to an external instruction of starting the snapshot simulation function to start the snapshot simulation function and turning off the valid flag of the snapshot simulation function according to an external instruction of terminating the snapshot simulation function; snapshot simulation function control means for inquiring with said updating range determination means and receiving notice of the bits on the bitmap corresponding to the range of update data, setting the corresponding bits on the bitmap in said bitmap information storage means by said bitmap information updating means, and executing data updating processing, if the valid flag of the snapshot simulation function is on when a data updating request is issued; and snapshot simulation result reporting means for checking the number of bits set on the bitmap of said bitmap information storage means, calculating and storing the number of bits multiplied by a management unit size as a physical disk capacity of a snapshot, resetting all bits on the bitmap of said bitmap information storage means by said bitmap information updating means, and reporting the physical disk capacity of the stored snapshot according to an external instruction of reporting the simulation result, when receiving an instruction of terminating the snapshot simulation function from said snapshot simulation function management means.