Patent ID: 7360016

Claim:
A method of protecting data in the cache memory of a storage system for protecting data in the cache memory of a first storage system and a second storage system coupled together and with a battery backed function, a method comprising the steps of: (a) detecting the operation status of the first storage system and reserving an area in the random access memory (RAM) of the second storage system; (b) monitoring an instruction given by a user on the disk cache of a first storage system and storing/deleting the data, corresponding to the data stored in the disk cache of the first storage system, in an second storage system according to an instruction; (c) when the first storage system is power failure, writing the data stored in the disk cache of the second storage system into the storage device thereof and controlling the storage device of the first storage system by the second storage system, writing a data of the disk cache of the first storage system stored in a second storage system into the storage device of the first storage device, and providing a server function to the first storage system through the second storage system; (d) monitoring the instruction given by the user on the disk cache of the second storage system and storing/deleting the corresponding information of the disk cache item from the reserved area according to the instruction; (e) using the battery backed function to provide power to the RAM of the second storage system when the second storage system is power failure; (f) reading the information of the disk cache item stored in the reserved area and preserving the data stored at the corresponding location in the RAM in accord with the information when the second storage system resumes; (g) reading the information of the disk cache item stored in the reserved area and writing the data stored in the corresponding location of the RAM into the corresponding storage device in accord with the information after the second storage system resumes; (h) stopping the server function of the first storage system and writing the data that are stored in the disk cache of the second storage system and need to be written into the storage device of the first storage system into the storage device of the first storage system after the first storage system resumes; and (i) stopping the control of the storage device of the first storage system by the second storage system, writing the data stored in the disk cache of the second storage system into the storage device of the second storage system, removing the information stored in the reserved area, and executing step (a).