Method and apparatus for increasing an amount of memory on demand when monitoring remote mirroring performance

A method of increasing an amount of memory in a queuing area on demand in a storage system implementing a remote mirroring function, said storage system including first and second storage subsystems which are connected to each other via a path and the first storage subsystem being connected to a host, the method comprising the steps of:

• providing a primary volume to the first storage subsystem and a remote secondary volume to the second storage subsystem, the remote secondary volume being a copied volume of the primary volume, the primary volume and the remote secondary volume being operated in the asynchronous mode;
• providing a first memory in a queuing area of the first storage subsystem and a second memory in a queuing area of the second storage subsystem for temporarily storing data transferred from the first storage subsystem to the second storage subsystem in response to a write input/output (I/O) issued by the host to write data in the primary volume;
• retrieving data temporarily stored in the second memory and storing the data in the remote secondary volume;
• and
• monitoring an unused area of the queuing area of the first storage system and increasing an amount of the first memory therein when the unused area becomes less than a predetermined amount.

A storage system comprising:

• a first storage apparatus which is connected to a host and includes a primary volume and a queuing area having a memory for temporarily storing data transferred from the first storage subsystem to the second storage subsystem in response to a write input/output (I/O) issued by the host to write data in the primary volume;
• and
• a second storage apparatus which is connected to said first storage apparatus via a path and includes a remote secondary volume,
• wherein the remote secondary volume is a copied volume of the primary volume and the primary volume and the remote secondary volume are in asynchronous mode, wherein an unused area of the queuing area is monitored and an amount of the memory therein is increased when the unused area becomes less than a predetermined amount.