Method and apparatus for providing system level errors in a large disk array storage system

DETAILED DESCRIPTION In accordance with the present invention a storage system is provided which includes at least one host controller that serves as an interface between a host computer and the storage system.
The host controller is responsive to a first set of commands (for example the SCSI command set) for performing a corresponding first set of operations.
The first set of operations may include those tasks necessary to effectuate the reading and writing of data to a storage device within the storage system.
The storage system further includes a memory which is accessible by the controller and is useful for temporarily storing data transferred to and from the host computer.
The memory is also used to store error information associated with various components of the storage system.
Generally, the error information is not normally available for reading by the host computer using the commands included in the first command set.
That is, a host computer would not be able to transmit any one of the commands in its standard form to the host controller and expect to have the error information stored in the memory returned as a return value.
The host controller within the storage system includes a command processor for receiving and executing commands as they are received from the host.
The command processor is further responsive to receipt of a modified command, from the first command set, for retrieving the error information stored in the memory and transmitting it back to the host which issued the command.
To achieve this access, the host controller recognizes that a specialized version of one of the commands has been received.
In order to recognize the modified command, the command processor is programmed to examine certain parameters of the received command and to determine if the command includes the special parameters which define the special memory access.
If the command includes those parameters, the special command is executed.
Otherwise, the standard operation associated with the command is performed