Method and apparatus for providing logical devices spanning several physical volumes

In a storage system including a host controller, a storage controller, a shared memory, and a plurality of storage devices and a corresponding plurality of device records associated with said storage devices, wherein said device records function to queue incoming commands from a host computer, a method of operating said storage system comprising the steps of:

• establishing a subset of said plurality of storage devices to function as a single addressable storage device (META DEVICE) as seen by said host computer;
• modifying header portions of associated ones of said device records to indicate that said associated ones of said storage devices are members of the META DEVICE;
• receiving by said host controller, an input/output (I/O) command directed to said META DEVICE;
• storing said I/O command in a device record corresponding to a first device in said META DEVICE;
• analyzing said I/O command to determine which one of said subset of storage devices should perform said I/O command and copying said I/O command to a corresponding one of said device records;
• and
• executing said I/O command, wherein said executing step further includes the steps of:
• placing an entry in a mailbox associated with said one of said subset of storage devices, said mailbox residing in said shared memory;
• retrieving, by said storage controller, said entry in said mailbox;
• and
• performing a data transfer with said one of said subset of storage devices.