Patent ID: 7702823
Filing Date: 2010-04-20
Classification: G06F

Abstract:
1. A disk subsystem, comprising: plural drive enclosures which store disk drives; and a disk controller which controls transfer of data stored in the disk drives between the drive enclosures and a host computer, wherein the drive enclosures each comprise a backend switch which is coupled to at least two of the disk drives and to the disk controller via at least four communication lines, wherein the backend switch comprises at least four switch ports including a first data communication port connected to one of the at least two disk drives through a first communication line, a second data communication port connected to another of the at least two disk drives through a second communication line, a third data communication port connected to the disk controller through a third communication line, and a status monitoring port, connected to the disk controller through a fourth communication line, separate from the third communication line, through which operation status of the switch ports of the backend switch is outputted, wherein the disk controller monitors a fault of the switch ports through the status monitoring port, wherein an indication of the fault being detected in one of the first, second or third data communication ports is provided to the disk controller through the status monitoring port and the fourth communication line connected between the status monitoring port and the disk controller, wherein the disk controller controls the backend switch to block one of the first and second data communication ports when the fault is detected in one of the first and second data communication ports while not blocking the other of the first and second data communication ports when no fault is detected in said other of the first and second data communication ports, and wherein the disk controller blocks the backend switch when every switch port included in the backend switch is blocked by the fault so that the backend switch is cut off from the disk subsystem, wherein said disk subsystem further comprises: a fault detecting unit which detects the fault in the switch ports; and an error handler which counts number of faults detected by the fault detecting unit, compares the number of faults and a predetermined threshold for each fault type, and provides the disk controller with fault information of the switch ports based on results of the comparison to thereby identify which one of the switch ports have the fault, wherein: the disk controller judges whether the fault corresponds to a failed switch port is a drive port to which one of the disk drives is connected, the disk controller judges whether one of the disk drives is accessible through a redundant port and a redundant path when the judged fault corresponds to the failed switch port being the drive port, the disk controller determines that the fault has occurred in at least one of the backend switch and a transmission line that connects the backend switch and the disk drives when the disk controller judged that the disk drive is accessible through the redundant port and the redundant path, and the disk controller determines that the fault has occurred in the disk drive when the disk controller judged that the disk drive is not accessible through the redundant port and the redundant path.