Abstract:
A system and method for isolating faulty connections in a storage area network, by identifying faulty passive connectivity components in both laboratory and customer site environments. Being independent of the operating system, protocol and components of the Storage Area Network (SAN) the method is passive with respect to live data transmissions within the SAN and is capable of testing the access and reach ability to all the active devices without impacting or changing the configuration and the setup parameters. The method enables the execution of a plurality of procedures including a host/client procedure, a host_switch procedure and an array controller procedure. The system may be a faulty connection and loss of access detection mechanism connected to the SAN or integrated within a SAN component device.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention generally relates to the field of failure detection within computer networks and particularly to a system and method for isolating faulty connections in a storage area network.  
         BACKGROUND OF THE INVENTION  
         [0002]    The diversity of the applications and the configuration complexity in a Storage Area Network (SAN) environment has presented a number of challenges in isolating failures. In bringing Fibre channel solutions to market, generally the focus of the user and the equipment manufacturers has been on how to isolate faults they believe have occurred in their products. For example, when a failure is detected a user such as, a lab technician, engineering support team member, customer and the like may point out that the problem is due to the functionality of one of the devices of the SAN, such as the host adapter, the switch, the hub or the array controller (e.g., disk array controller). Replacing such devices can be costly and time consuming and may not ensure proper functionality of the SAN.  
           [0003]    However, this failure analysis is typically presented without checking the functionality of the passive connectivity components such as Giga-Bit Interface Convertors (GBICs), cables, connectors, device ports and the like. Failure of these connectivity components can render a SAN or the SAN fail-over capabilities inoperable. Consequently, the user may be unable to determine why the SAN is inoperable even though the intelligent components appear functional. Thus, the perception of the SAN reliability, access, serviceability, usability, integrity and redundancy capabilities may be severely impacted, even though such failure may only cause system down time with no loss of information.  
           [0004]    Currently, there exists no method that assists users in isolating failures, whether at a lab or a customer site, for all the certified operating systems, protocols and topologies and avoids having any effect on the SAN capabilities with respect to live data transmissions. It may be beneficial to provide a system and method that a user may utilize to perform a failure isolation technique. This is of particular importance, for as the technology continues to mature and become more sophisticated so may the connectivity components designed to connect them into a single operational unit. Thus, the difficulty of isolating faulty connections without disrupting the operating system can be expected to increase.  
           [0005]    Therefore, it would be desirable to provide a system and method for isolating faulty connections in a storage area network thereby allowing a user to easily identify faulty passive connectivity components and eliminate the unnecessary replacement of functional devices.  
         SUMMARY OF THE INVENTION  
         [0006]    Accordingly, the present invention is directed to a system and method for isolating faulty connections in a storage area network by identifying faulty passive connectivity components in a variety of environments such as, lab sites, customer sites and the like. The method is passive with respect to live data transmissions within the SAN, being independent of the operating system, protocol and components of the Storage Area Network (SAN), and is capable of testing the access and reach ability to active devices within the SAN without impacting or changing the configuration and the setup parameters.  
           [0007]    In exemplary embodiments, the system and method may be implemented by an information handling system with a connectivity scan, coupled to the SAN for identifying and locating faulty connections and loss of access to devices. The connectivity scan enables the execution of a plurality of procedures upon the SAN, which provide a user the ability to identify and isolate faulty connections within a variety of passive connectivity components located in various sections of the SAN environment.  
           [0008]    In another embodiment, the plurality of procedures includes a host/client procedure which issues a report exchange status (RES) request to a connectivity component listed in a host configuration, the host receives an accept response or no response from the connectivity component. The host then generates and stores a list of faulty connections based on the response by the connectivity components to the RES request. A host_switch procedure provides analysis of the list of possible faulty connections in order to determine if the failure is due to a connection between a host and a switch or the switch is faulty. This is accomplished by checking if the device under investigation logged to the switch or not. An array controller procedure transmits an echoing probe signal from an array controller along the faulty path indicated from the list of possible faulty connections to determine if there is a connection failure between the target component and the array controller component.  
           [0009]    It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description serve to explain the principles of the invention. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0010]    The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which:  
         [0011]    [0011]FIG. 1 is an illustration of an exemplary embodiment of the present invention wherein a Storage Area Network (SAN) is shown;  
         [0012]    [0012]FIG. 2. is a block diagram of an exemplary embodiment of the present invention wherein a section of the SAN including the connectivity scans are shown;  
         [0013]    [0013]FIG. 3 is a flow chart of an exemplary embodiment of the present invention wherein the steps of application of the procedures implementable by the connectivity scan mechanism are shown;  
         [0014]    [0014]FIG. 4 is a flow chart of an exemplary embodiment of the present invention wherein the steps for the execution of a host/client procedure are shown;  
         [0015]    [0015]FIG. 5 is a flow chart of an exemplary embodiment of the present invention wherein the steps for the execution of a host_switch procedure are shown;  
         [0016]    [0016]FIG. 6 is a flow chart of an exemplary embodiment of the present invention wherein the steps for the execution of an array controller procedure are shown; and  
         [0017]    [0017]FIG. 7 is a block diagram illustrating an exemplary hardware architecture of an information handling system suitable for implementing the connectivity scan. 
     
    
     DETAILED DESCRIPTION  
       [0018]    The present invention provides a system and method for isolating faulty connections within a Storage Area Network (SAN) environment. Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.  
         [0019]    [0019]FIG. 1 illustrates a typical SAN Fibre Channel environment employing a system for isolating faulty connections in accordance with an exemplary embodiment of the present invention. However, the system and method employed by the current invention is applicable to any protocol, such as, SCSI, iSCSI, InfinBand and the like. As shown in FIG. 1, a Storage Area Network (SAN)  100  includes one or more servers  102 ,  104  and  106  with host adapters  108 ,  110  and  112  residing within, a switch  114  and storage arrays  116 ,  118  and  120  interconnected via network connection  122  and Fibre Channel cable  140 . SAN  100  further includes an information handling system  150  and an Ethernet Hub  154 , which forms a public network and uplinks with a Virtual Local Area Network (VLAN)  156 . Information handling system  150 , Ehternet Hub  154  and VLAN  156  are connected to the network via network connection  122 . Information handling system  150  may be connected directly to switch  114  via Fibre Channel cable  160  and storage arrays  116 ,  118  and  120  via serial connections  162 ,  164  and  166 , respectively. In embodiments of the invention, storage arrays  116 ,  118  and  120  are comprised of array controllers  124 ,  126 ,  128 ,  130 ,  132  and  134  and drive enclosures providing data storage. In exemplary embodiments, the storage arrays are disk storage arrays and the array controllers are disk array controllers, however, other storage system technologies such as tape array storage, network array storage (NAS), and the like, may be employed without departing from the spirit and scope of the present invention.  
         [0020]    Servers  102 ,  104  and  106  may employ a variety of server operating systems, for example, Windows 2000, Windows NT, Solaris, Netware, IRIX, HP-UX, Linux, AIX and the like. The servers may each employ the same operating system or may each employ a different operating system forming a heterogeneous environment.  
         [0021]    Host adapters, switches, hubs and array controllers are connected by Fibre Channel cable  140 . Passive connectivity components, such as, Giga-Bit Interface Converters (GBICS), connectors, device ports and the like are employed. It is contemplated that other connectivity components may be employed by one of ordinary skill in the art without departing from the scope and spirit of the present invention.  
         [0022]    Information handling system  150  executing a connectivity scan  152  for isolating faulty connections due to faulty connectivity components, is provided. Connectivity scan  152  is implemented as executable programs resident in the memory of information handling system  150 . Information handling system  150  may be a personal computer, handheld computer, and the like, configured generally as described in FIG. 7, discussed more fully below. There may be one or more information handling systems included in SAN  100 . Information handling system  150  is coupled to the SAN via network connection  122 . A user may also hot plug a device to a fabric switch or loop behind a switch to implement connectivity scan  152 .  
         [0023]    Information handling system  150  may be directly connected to switch  114  via a Fibre Channel cable  160 . Further, information handling system  150  may be individually, directly connected to each of the storage arrays  116  through  120  via serial connections  162 ,  164  and  166 . Fibre channel cable  160  and serial connections  162  through  166  provide information handling system  150  the ability to execute connectivity scan  152  directly upon switch  114  and storage arrays  116  through  120  as well as the ability to provide those devices with the necessary information so that they may execute an appropriate procedure of connectivity scan  152 . Serial connections  162  through  166  and Fibre Channel cable  160  may employ other technologies as may be contemplated by one or ordinary skill in the art.  
         [0024]    Connectivity scan  152  may be executed locally, as shown, or may be executed remotely over the uplinked VLAN  156 . For example, an engineering support team member in location X may execute connectivity scan  152  on a customer SAN in location Y through the VLAN uplink  156  to Ethernet Hub  154 , which serves the SAN of the customer.  
         [0025]    The connectivity scan  152  provides multiple executable procedures for performing diagnostic functions as well as analysis functions on the various Fibre Channel connectivity components within SAN  100 . These procedures may be utilized by a variety of users, such as, the customer, engineering support team members, systems integrators and the like. In the preferred embodiments of the invention the executable procedures include: (1) Host/Client procedure; (2) Host_Switch procedure; and (3) Array Controller procedure.  
         [0026]    If SAN  100  does not include a device such as, information handling system  150  for implementation and execution of connectivity scan  152  then connectivity scan  152  may be executed from any one of servers  102 ,  104 ,  106  or all of the servers at the same time. Therefore, Host/Client procedure, Host_Switch procedure and Array Controller procedure may be executed from information handling system  150  and any one of or all of the servers  102  through  106 . Host_Switch procedure may be executed from switch  114  and the Array Controller procedure may be executed from any one of the Array Controllers  124  through  134 . Array Controller procedure may be only executed over SAN  100  or through the serial connections.  
         [0027]    These procedures operate to isolate the faulty connection by the systematic elimination of connectivity components, which are functioning properly. In one embodiment the structured approach employed starts from the host, the initiator device, and tests the host access to other components, the target devices, in the SAN  100  system. The target devices in this example may include the switch, the hub, the array controller or other components connected within the SAN environment. The host transmits a signal probe with a response request to the target devices. If all target devices respond to the request then no fault is found and another signal probe, which originates at the array controller module, is sent out. The process and method is discussed fully in FIGS. 3 through 6 below. It is contemplated that the connectivity scan may be initiated from any device or component located within the SAN and target any other device or component within the SAN.  
         [0028]    Referring now to FIG. 2, a block diagram of the present invention wherein a section  200  of SAN  100  including a connectivity scan  202  and  204  in accordance with an exemplary embodiment is shown. In this embodiment, connectivity scan  202  and  204  are integrated with Host/Client  206  and Array Controller Module  208 . Thus, connectivity scan  202  and  204  do not require an additional information handling system for implementation. Three connectivity component pathways  210 ,  212  and  214  connect Host/Client  206  with Switches  220 , Hubs  222  and Array Controller Module  208 . Connectivity component pathway  214  provides a direct connection between Host/Client  106  and Array Controller Module  208 . Two additional connectivity component pathways  216  and  218  connect Array Controller Module  208  with Switches  220  and Hubs  222 . FIG. 2 shows one host/client connection, however, it may be understood that such connection schemes may be implemented with any number of host/clients within a SAN. Any number of cascaded hubs and cascaded switches may be included within the systems of FIGS. 1 and 2 without departing from the scope and spirit of the present invention.  
         [0029]    Connectivity scan mechanism  202 , integrated with Host/Client  206 , implements a host/client procedure and a host_switch procedure each of which is fully discussed in FIGS. 4 and 5 respectively. As shown in FIG. 1, each storage system  116 ,  118  and  120  includes two array controllers. Each array controller makes up an array controller module  208 . As is more fully discussed below in FIG. 6, connectivity scan mechanism  204 , integrated with array controller module  208 , implements an array controller procedure  600 .  
         [0030]    Referring now to FIG. 3 a flow chart of an exemplary method of the present invention wherein the steps of faulty connection determination  300  of the procedures implementable by the connectivity scan mechanism are shown. Step  302  is the host/client procedure, which initiates diagnosis of faulty connections by sending a signal probe and then generating and storing a list of possible faulty connections, which is used by each of the following steps. The host/client procedure issues a report exchange status (RES) request to each device listed in the host configuration. If the target device returns an accept response to the RES request then the path is good. Otherwise, there may be a possible faulty connection with the path. The host generates the list of the possible faulty connections. This list is used by the components, such as the switch  220 , the hub  222  and the array controller module  208  shown in FIG. 2.  
         [0031]    Step  304  is the host_switch procedure, which provides analysis of the list and further refines the search for a faulty connection. This procedure uses the list generated in step  302  to determine if the failure is due to a connection between the host and the switch or a bad switch. The failure determination is refined by checking if the device under investigation is logged in to the switch or not. If the device is logged in then the fault is due to a connection between the host and the switch. If the switch shows the host adapter is logged in but not the device then the fault may be due to a connection between the switch and the device. If the switch shows the host adapter logged in and the device logged in then the procedure checks the functionality of the switch and rescans the devices.  
         [0032]    Step  306  is the array controller procedure. By using the list generated in step  302  and not resolved by executing the Host_Switch of step  304 , this procedure determines if there is a connection failure between the target and another connectivity component, such as the array controller module. This is determined by echoing probe signals from the array controller module along the faulty path indicated in the list generated by step  302 . Based on the echo outcome one of three options may be executed. The options are (1) Checking the physical connections, (2) checking the connectivity components diagnostics and (3) verifying nominal operations or a verification process for each component along the  1 / 0  path.  
         [0033]    Referring now to FIG. 4 a flow chart wherein the steps for the execution of a host/client procedure  400  in accordance with an exemplary method of the present invention are shown. Step  402  begins the procedure by identifying all the host/clients connected within the SAN. From the identification, step  404  generates a hostindex assigning a number to each host/client from 1 to N where N equals the number of host/clients in the SAN. Once each host/client has been identified then the procedure may either terminate the procedure by going to the connectivity probe complete step of  430  or go on to step  406 . Step  406  generates a list of all target devices (e.g., switches, hubs, array controller modules, and the like) that are detected by an individual host/client within the SAN.  
         [0034]    Step  408  generates a deviceindex assigning a number to each target device from 1 to N where N equals the number of host target devices. Step  410  sends the probe signal to a target device. In the Fibre Channel environment of this embodiment the signal is a report exchange status (RES) signal. It is contemplated that other technologies may be employed to enable SAN  100  and, therefore, other signals may be utilized, such as, Ping-Ethernet, Tur-SCSI (test unit ready command-SCSI) and the like. In step  412  the host/client is awaiting a response from the target device to which it sent the signal probe. If the host/client receives no response then in step  414  it acknowledges that a possible bad path is detected. From this bad path detected acknowledgment the host/client generates a “Record List (Host_Path Faults) path integrity for Host (hostindex, deviceindex),” which stores the possibly faulty connection path. The procedure loops back to steps  408 ,  410  and  412  for each target device until it has checked each target device. If the host/client detects more than one possibly faulty connection path it is recorded as described in step  414 . If the host/client receives an accept response from the target device then the procedure loops back to step  408 . At step  408  the procedure checks to see if there are any other target devices listed in the deviceindex, which need to be checked. If there are target devices which need to be checked then the procedure continues by sending the probe signal, of step  410 , to the next target device. This loop from  408  through  412  keeps repeating until all devices are checked. When all target devices have been checked and all possibly faulty connections recorded then the procedure proceeds to step  420 .  
         [0035]    Step  420  establishes a pathindex assigning a number from 1 to N for each faulty path detected and recorded on the Record List Host_Path_Faults. This creates a Host(pathindex) of all the possibly faulty connections. In step  422  each path identified in the Host(pathindex) is analyzed for path integrity. In step  424  the procedure determines if the individual path has been established or not. If the path has not been established then the procedure proceeds to step  426  wherein the faulty path condition is documented. This documentation provides the list of faulty connections that is utilized by the Host_Switch procedure and the Array Controller procedure. Once documentation is complete, step  428  escalates the failure from a possibility to a verified faulty connection. After escalation the procedure loops back to step  420  to check the other pathways identified. If in step  424  a path is verified as having been established then the procedure loops back to step  420  to check the other pathways identified. When step  420  recognizes that it has checked all pathways and documented those that are faulty, then the procedure proceeds to step  430  and recognizes that the connectivity probe is complete.  
         [0036]    Referring now to FIG. 5 a flow chart wherein the steps for the execution of a host_switch procedure  500  in accordance with an exemplary embodiment of the present invention are shown. This procedure starts from step  422  of FIG. 4 which is the analysis of path integrity for each bad path recorded for the Host(pathindex). In step  502  the procedure identifies the connectivity devices along the Host(pathindex) from the host to the target device. From this identification, step  504  generates a connectivityindex assigning a value from 1 to M for all the possible faulty connectivity devices. In step  506  connected device information, for each connected device identified in the connectivityindex, is gathered (i.e. Fabric Login, Loop Online). In step  508  the connectivityindex information set is compared against the hostindex and Host(deviceindex) information sets. In step  510  the procedure determines if the information sets match. If they match then the procedure loops back to step  504  and begins the process for another connectivity device. If the information sets do not match then the procedure proceeds to step  512  where the connectivity device is placed on a list, comprising all faulty paths discovered (Host_SW_Fault_List). After the connectivity device has been placed on the list the procedure loops back to step  504  and begins the process for another connectivity device. Once the procedure recognizes that all connectivity devices have been checked it proceeds to step  514 .  
         [0037]    Step  514  generates a faultindex assigning values from 1 to F for all faulty paths recorded in the Host_SW_Fault_List. In step  516  the procedure checks the connection of each connectivity component between the host and the connectivity device. The connectivity components may include Fibre cable, Gig-Bit Interface Converters and device ports such as disk drives, host adapters, array controllers or any communicating device in a SAN environment. The procedure in step  518  performs a scan of the Host Software indicated as Host_SW_Scan. This scan is performed automatically checking all connectivity devices between the host and the switch. It is contemplated that this scan may also be performed manually without departing from the spirit and scope of the present invention. If in step  520  the software scan determines that the fault has been eliminated as then the procedure loops back to step  514 . If step  520  cannot eliminate the fault then a diagnostic is run on the switch in step  522 . Step  524  determines if the switch diagnostic indicates the switch has failed or not. If the diagnostic fails, then the switch is functioning and the procedure performs a SAN Topology Component Verification in step  526 . This is a verification that all connections between the host and the switch are functioning properly and may be indicative of a functional component failure. If the diagnostic is successful in identifying the switch as the fault source then step  528  indicates that the switch may be repaired or replaced at which point the procedure loops back to step  516 . Once all faulty paths have been checked and the switch eliminated as the fault source or repaired or replaced the procedure establishes a return connection in step  530 .  
         [0038]    Referring now to FIG. 6 a flow chart wherein the steps for the execution of an array controller procedure  600  in accordance with an exemplary embodiment of the present invention are shown. Step  602  initiates an array controller connectivity scan for each bad path recorded for Host(pathindex). In step  604  the number of target devices identified are indexed and placed into a targetindex where values from 1 to T are assigned. After the target devices have all been identified then the array controller connectivity scan sends out a probe signal in step  606  to each target device. This is an echoing signal probe sent from the array controller module end of a communication path and tracking back towards a target device.  
         [0039]    The type of signal sent depends on the device type, which is determined in step  608 . The process, which takes place in step  608 , of identifying the type of target device is represented by steps  610  through  626 . Step  610  determines if the target device identified is a Fibre Channel switch. If step  610  determines the target device is a Fibre Channel switch then in step  612  the array controller procedure initiates an echo RES signal probe. If step  610  determines that the target device is not a Fibre Channel switch then the process proceeds to step  614 . Step  614  determines if the target device identified is a Fibre Channel hub. If at step  614  it is determined that the target device is a Fibre Channel hub then in step  616  the procedure disables the switch port before proceeding to step  618  where it initiates an echo NOP (No Operation) signal probe. If step  614  determines that the target device is not a Fibre Channel hub then the process proceeds to step  620 . Step  620  determines if the target device identified is a Fibre Channel array controller module where the host/client is directly connected with the array controller module. If step  620  determines that the target device is a Fibre Channel array controller module then step  622  initiates an echo NOP signal probe. If step  620  determines that the target device is not a Fibre Channel array controller module then the process proceeds to step  624 . Step  624  applies to any remaining target device which is connected by a SCSI bus. These serially connected target devices, in step  626 , have an echo TUR (Test Unit Ready) signal probe sent out to them.  
         [0040]    These signal probes may be automated using a script language. The script language may be executed from information handling system  150  running serial software such as, PROCOM and the like. It is also contemplated that the script language may be executed from one or all of the servers  102  through  106  and may be executed across a network via Ethernet Hub  154 , which may uplink VLAN  156 .  
         [0041]    Following each echo probe signal sent to a target device identified in the targetindex, step  628  determines if the echo status return has failed or not. If the echo status return is not a failure then the procedure loops back to step  606  and begins another series of signal probe scans. If the echo status return is a failure then in step  630  all connections between the host and the connectivity device are checked (i.e. cables, device port condition, Giga-Bit Interface Converters, and the like). After completing the check, step  632  initiates a Host_SW_Scan, like the one performed in step  518  of FIG. 5, where the software scans to identify the location of the fault.  
         [0042]    The scan performed in step  632  then determines in step  634  if the Host(PathIndex) is marked bad in the Host_PathList. If the procedure determines that step  634  is false then it loops back to step  604 . If the procedure determines that step  634  is true then in step  636  a diagnostic is run on the device(s) connecting the switch, hub and the like, and the components themselves. In step  638  the procedure determines if the connectivity diagnostic has identified a failed connectivity device. If the diagnostic has identified a failed connectivity device then step  640  directs the user to replace or repair the device and then loops back to step  606  to initiate an echo probe on another device. If the diagnostic fails to identify a faulty device then the procedure, in step  642 , performs a SAN Topology Component Verification scan to verify that all connections are functional between the array controller and the target device. After it has finished the SAN Topology Component Verification scan the procedure then loops back to step  604 .  
         [0043]    Once the procedure has checked the connectivity of each target device and replaced or repaired any faulty connectivity components, which resulted in faulty connections, the procedure through step  604  proceeds to step  644  where a functioning return connection has been established. At this point the connectivity scan is complete with all faulty connections identified and returned to active status.  
         [0044]    Referring now to FIG. 7, an exemplary hardware system generally representative of an information handling system is shown. The hardware system  700  is controlled by a central processing system  702 . The central processing system  702  includes a central processing unit such as a microprocessor or microcontroller for executing programs, performing data manipulations and controlling the tasks of the hardware system  700 . Communication with the central processor  702  is implemented through a system bus  710  for transferring information among the components of the hardware system  700 . The bus  710  may include a data channel for facilitating information transfer between storage and other peripheral components of the hardware system. The bus  710  further provides the set of signals required for communication with the central processing system  702  including a data bus, address bus, and control bus. The bus  710  may comprise any state of the art bus architecture according to promulgated standards, for example, industry standard architecture (ISA), extended industry standard architecture (EISA), Micro Channel Architecture (MCA), peripheral component interconnect (PCI) local bus, standards promulgated by the Institute of Electrical and Electronics Engineers (IEEE) including IEEE 488 general-purpose interface bus (GPIB), IEEE 696/S-100, and so on. Other components of the hardware system  700  include main memory  704  and auxiliary memory  706 . The hardware system  700  may further include an auxiliary processing system  708  as required. The main memory  704  provides storage of instructions and data for programs executing on the central processing system  702 . The main memory  704  is typically semiconductor-based memory such as dynamic random access memory (DRAM) and/or static random access memory (SRAM). Other semi-conductor-based memory types include, for example, synchronous dynamic random access memory (SDRAM), Rambus dynamic random access memory (RDRAM), ferroelectric random access memory (FRAM), and so on. The auxiliary memory  706  provides storage of instructions and data that are loaded into the main memory  704  before execution. The auxiliary memory  706  may include semiconductor based memory such as read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable read-only memory (EEPROM), or flash memory (block oriented memory similar to EEPROM). The auxiliary memory  706  may also include a variety of non-semiconductor-based memories, including but not limited to magnetic tape, drum, floppy disk, hard disk, optical, laser disk, compact disc read-only memory (CD-ROM), write once compact disc (CD-R), rewritable compact disc (CD-RW), digital versatile disc read-only memory (DVD-ROM), write once DVD (DVD-R), rewritable digital versatile disc (DVD-RAM), etc. Other varieties of memory devices are contemplated as well. The hardware system  700  may optionally include an auxiliary processing system  708  which may be an auxiliary processor to manage input/output, an auxiliary processor to perform floating point mathematical operations, a digital signal processor (a special-purpose microprocessor having an architecture suitable for fast execution of signal processing algorithms), a back-end processor (a slave processor subordinate to the main processing system), an additional microprocessor or controller for dual or multiple processor systems, or a coprocessor. It may be recognized that such auxiliary processors may be discrete processors or may be built in to the main processor.  
         [0045]    The hardware system  700  further includes a display system  712  for connecting to a display device  714 , and an input/output (I/O) system  716  for connecting to one or more I/O devices  718 ,  720 , and up to N number of I/O devices  722 . The display system  712  may comprise a video display adapter having all of the components for driving the display device, including video memory, buffer, and graphics engine as desired. Video memory may be, for example, video random access memory (VRAM), synchronous graphics random access memory (SGRAM), windows random access memory (WRAM), and the like. The display device  714  may comprise a cathode ray-tube (CRT) type display such as a monitor or television, or may comprise an alternative type of display technology such as a projection-type CRT display, a liquid-crystal display (LCD) overhead projector display, an LCD display, a light-emitting diode (LED) display, a gas or plasma display, an electroluminescent display, a vacuum fluorescent display, a cathodoluminescent (field emission) display, a plasma-addressed liquid crystal (PALC) display, a high gain emissive display (HGED), and so forth. The input/output system  716  may comprise one or more controllers or adapters for providing interface functions between the one or more I/O devices  718 - 722 . For example, the input/output system  716  may comprise a serial port, parallel port, universal serial bus (USB) port, IEEE 1394 serial bus port, infrared port, network adapter, printer adapter, radio-frequency (RF) communications adapter, universal asynchronous receiver-transmitter (UART) port, etc., for interfacing between corresponding I/O devices such as a keyboard, mouse, trackball, touchpad, joystick, trackstick, infrared transducers, printer, modem, RF modem, bar code reader, charge-coupled device (CCD) reader, scanner, compact disc (CD), compact disc read-only memory (CD-ROM), digital versatile disc (DVD), video capture device, TV tuner card, touch screen, stylus, electroacoustic transducer, microphone, speaker, audio amplifier, etc. The input/output system  716  and I/O devices  718 - 722  may provide or receive analog or digital signals for communication between the hardware system  700  of the present invention and external devices, networks, or information sources. The input/output system  716  and I/O devices  718 - 722  preferably implement industry promulgated architecture standards, including Ethernet IEEE 702 standards (e.g., IEEE 702.3 for broadband and baseband networks, IEEE 702.3z for Gigabit Ethernet, IEEE 702.4 for token passing bus networks, IEEE 702.5 for token ring networks, IEEE 702.6 for metropolitan area networks, and so on), Fibre Channel, digital subscriber line (DSL), asymmetric digital subscriber line (ASDL), frame relay, asynchronous transfer mode (ATM), integrated digital services network (ISDN), personal communications services (PCS), transmission control protocol/Internet protocol (TCP/IP), serial line Internet protocol/point to point protocol (SLIP/PPP), and so on. It may be appreciated that modification or reconfiguration of the hardware system  700  of FIG. 7 by one having ordinary skill in the art would not depart from the scope or the spirit of the present invention.  
         [0046]    In the exemplary embodiments, the methods disclosed may be implemented as sets of instructions or software readable by a device. Further, it is understood that the specific order or hierarchy of steps in the methods disclosed are examples of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the method can be rearranged while remaining within the scope and spirit of the present invention. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.  
         [0047]    It is believed that the system and method for isolating faulty connections in a storage area network of the present invention and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely an explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.