Abstract:
The present invention is directed to an apparatus capable of dual porting a serial advanced technology attachment (SATA) disk drive in a fault tolerant communication system, such as fiber channel. The dual porting apparatus includes two idle regenerators coupled to two serial master devices, a synchronization logic capable of synchronizing the communications between one of the idle regenerators and a third idle regenerator coupled to the SATA disk drive. Furthermore the dual porting apparatus may include an auto detector capable of enabling either of the first two idle regenerators, thus effectively switching between the two.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application and claims priority under 35 U.S.C. §120 to U.S. non-provisional application Ser. No. 10/025,256 entitled: Dual Porting Serial Advanced Technology Attachment Disk Drives for Fault Tolerant Applications filed Dec. 19, 2001, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to the field of data storage, and particularly to a system for utilizing serial disk drives in fault tolerant multi-initiated applications. 
     BACKGROUND OF THE INVENTION 
     Data storage has become increasingly important as information handling systems become capable of handling and communicating more data. Currently, improvements to data storage systems are aimed at increasing the amount of data and providing fault tolerant systems. While data storage systems have become more efficient at handling large amounts of data in a fault tolerant manner, typically such fault-tolerant data storage systems often are cost-prohibitive. 
     Expensive fault tolerant data storage systems therefore may not be implemented in certain situations where their cost is not justified by the design application. As a result, information handling systems often are configured with lower cost data storage systems. One example of this cost savings measure is in the implementation of serial advanced technology attachment (SATA) disk drives in place of fibre channel disk drives. 
     Current fibre channel disk drives are multi-ported and offer fault tolerant interfacing with external components. One of the drawbacks of including a fibre channel disk drive in a system is the drive&#39;s price difference. Presently fibre channel disk drives typically are between 3 to 6 times the price of a SATA disk drive, for a comparable storage capacity. Thus designers often may include a SATA drive instead of a fibre channel drive in certain applications. 
     While serial disk drive offer increased cost savings over fibre channel drives, the inherent single ported design are often a source of failure, thus, reducing the availability of data. It is this single point of failure which may cause designers either to include costly fibre channel disk drives or risk potential data loss. 
     Therefore, it would be desirable to provide a system and method for cost-effectively utilizing serial storage devices in a fault tolerant applications, thereby allowing for the utilization of more cost effective serial storage devices without the drawbacks inherent to a single ported system. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to an apparatus and method for implementing dual porting of an inherently single ported serial disk drive, such as a SATA disk drive. The inclusion of an apparatus of the present invention allows a single ported serial disk drive to operate, in a fault-tolerant system such as a system employing fibre channel based communication without the previously experienced fault drawbacks. 
     An apparatus for dual porting a serial disk drive of the present invention in the presently preferred embodiment is connected through the back panel of an information handling system utilizing a peripheral component interface (PCI) to a first and a second SATA master control devices which are operating in a fibre channel based communication system. In the present embodiment the dual porting apparatus is included in a disk drive canister board additionally containing a SATA disk drive. Further by including the dual porting apparatus in the disk drive canister board in the event of a failure the dual porting apparatus may be easily replaced. 
     In a further embodiment the dual porting apparatus contains a first and a second idle regenerator connected to a first and a second SATA master device, respectively. The first and the second idle regenerators being capable of transmitting and receiving signals to their respective SATA master devices. Included in the dual porting apparatus is a third idle regenerator connected to the first and the second idle regenerators. The third idle regenerator additionally connected to a serial disk drive, such as a SATA disk drive. The third idle regenerator is capable of receiving and transmitting signals to the serial disk drive. Further included in the dual porting apparatus is synchronization logic capable of synchronizing the transfer between one of the first idle regenerator and the second idle regenerator and the third idle regenerator. 
     Additionally, the dual porting apparatus, in contemplated embodiments, is capable of receiving control signals, thereby controlling which idle generator is enabled from a SATA master device. In further embodiments the apparatus for dual porting a serial disk drive includes an auto detector capable of determining the presence/absence of idle characters from the first and the second SATA master devices. Thus the auto detector may determine which SATA master device is active and thus enable a single SATA master device at a time. 
     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 THE DRAWINGS 
       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: 
         FIG. 1  is an overview illustration of an exemplary embodiment wherein an apparatus for dual poring a serial disk drive in an information handling system; 
         FIG. 2  is an overview illustration of an exemplary embodiment an apparatus for dual porting a serial disk drive in a disk drive canister board; 
         FIG. 3  is an overview illustration of an apparatus for dual porting a serial disk drive with capability for accepting control signal from an external source. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the presently preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     Referring generally now to  FIGS. 1 through 3 , exemplary embodiments of the present invention are discussed, wherein an apparatus for utilizing single ported serial disk drives, such as SATA disk drives in multi-ported fault tolerant applications are discussed. Fault tolerant storage systems such as fibre channel disk drives offer increased functionality over SATA drives which are subject to a single point of failure, thus reducing the availability of data to the system. 
     While fibre channel drives offer advantages over that of SATA drives, the high cost of fibre channel drives continues to be a factor in overall utilization. For example, fibre channel disk drives are often utilized in high performance information handling systems. Therefore, the current invention provides an apparatus to incorporate SATA drives into fault-tolerant applications without the previously experienced single point failure associated with SATA drives. 
     Referring now to  FIG. 1 , in a first embodiment of the present invention an apparatus for dual porting a serial disk drive  102 , such as a SATA drive  104 , is discussed. In the current embodiment, the dual porting apparatus  102  is included on a disk drive canister  114 . The present implementation allows for the utilization of the SATA drive  104  in a fibre channel environment without the drawbacks associated with single point failures. In the present embodiment, the dual porting apparatus  102  is employed as part of the disk drive canister  114  incorporated in an information handling system  100 . 
     Furthermore, the arrangement of disk drive canister  114  including associated SATA drives  104  and dual porting apparatus  102  allows for redundancy in the information handling system  100 , thus reducing the risk of a failure. 
     In the present embodiment, the dual porting apparatus  102  is connected to a first and a second SATA master devices  110  &amp;  112  through a back panel  106  of the information handling system  100  through peripheral component interfaces (PCI)  108  implemented in the first and second SATA master devices  110  &amp;  112 . It is to be understood that various interfaces may be employed as contemplated by one of ordinary skill in the art without departing from the spirit and scope of the present invention, and it is the intention of the present invention to encompass and include these variations. For example the present interface may be incorporated in a proprietary bus or the like. For present purposes the first and the second SATA master devices are substantially similar and are merely referred to as “first and second” SATA master devices  110  &amp;  112  for convenience. 
     In the present embodiment, the first and second SATA master devices  110  &amp;  112  individually include a fibre channel connection  116 . Furthermore, the first and second SATA master devices include a uniprocessor (uP)  118  and a memory  120 . 
     Additionally, in the present embodiment the SATA master devices  110  &amp;  112  are capable of providing control signals from a higher level to the dual porting apparatus  102  ensuring that only a single disk drive canister  114  is enabled at a time. In further embodiments, the first and the second SATA master devices  110  &amp;  112  are continuously enabled with controls executed at a higher level guaranteeing that only a single SATA master device is enabled at a time. For example, by sending control signals from a higher level, switching in the middle of a command is prevented. 
     Referring now to  FIG. 2 , a disk drive canister  200  including a dual porting apparatus  202  for porting a serial disk drive is discussed. In the present embodiment, the dual porting apparatus  202  may be connected between a SATA disk drive  204  and the back panel of an information handling system, such as the arrangement discussed in  FIG. 1 , thus effectively multiplexing the serial disk drive  204 . In the current embodiment the dual porting apparatus  202  is integrated in the disk drive canister  200  thus allowing for ease of replacement in the event of failure. 
     The present embodiment thus allows for the incorporation of the SATA disk drive  204  into a fault tolerant environment, such as fibre channel based systems without the drawback of a single failure point previously experienced with SATA drive included without the dual porting apparatus  202  of the present invention. Further, through implementation of the present invention the SATA drive  204  may continue to receive idle characters during utilization. 
     The dual porting apparatus  202  includes a first idle regenerator  206 . The first idle regenerator  206  is connected to a first serial master device, such as discussed in  FIG. 1 . The first idle regenerator  206  in the present embodiment is capable of transmitting and receiving signals to the first serial master device via an input/output connection  208 . In the current embodiment the input/output connection is made utilizing a PCI, although it is contemplated that other interfaces are capable of utilization for this purpose without departing from the scope and spirit of the present invention. For example, the interface may be implemented without a processor or be embodied in a proprietary bus, or the like. 
     The dual porting apparatus  202  of the present embodiment further includes a second idle regenerator  210 . The second idle regenerator  210  is connected to a second serial master device via input/output connection  212 . The second serial master device of the present embodiment is substantially similar to the second serial master device as discussed in  FIG. 1 . The second idle regenerator  210  is capable of receiving and transmitting signals to the second serial master device. Additionally, the second idle regenerator  210  is connected through connection  212  which is ported to the second serial master device though a PCI. 
     A third idle regenerator  214  is connected to the first and the second idle regenerators  206  &amp;  210  and additionally to the serial disk drive  204 . The third idle regenerator  214 , included in the dual porting apparatus  202 , is capable of transmitting and receiving signals from the first and second idle regenerators  206  &amp;  210  and the serial disk drive  204 , such as a SATA disk drive. 
     Further included in the dual porting apparatus  202 , is synchronization logic  216  connected to the first, second and third idle regenerators  206 ,  210  and  216  respectively. The synchronization logic  216  is capable of synchronizing data transfers between one of the first and second idle regenerators  206  &amp;  210  and the third idle generator  214 . For example, the synchronization logic  216  is capable of synchronizing the third idle regenerator  214  with the second idle regenerator in the event of a desired switch in data stream input from the first idle regenerator  206  to the second idle regenerator  210 . Furthermore, should an event occur which causes a disruption in synchronization in the dual porting apparatus, the synchronization logic  216  is utilized to reestablish synchronization between the third idle regenerator and the first or second idle regenerator as required by the circumstances. 
     In embodiments of the present invention the dual porting apparatus  202  further includes an auto detector  218 . The auto detector  218  in the present embodiment is connected to the input/output of the first and the second serial masters devices  208  &amp;  212 , respectively as well as the synchronization logic  216 . 
     For example, the auto detector  218  may be incorporated into the dual porting apparatus  102  which in turn is included in a disk drive canister  114  as discussed in  FIG. 1  or the like. The auto detector  218  is capable of automatically switching between the first and second master devices based on the presence or absence of idle characters transmitted by either of the first and second master devices. The auto detector  218  is further capable of controlling the switching between the first and second serial master devices, thus allowing the input/output of data between the dual porting apparatus and one of the first and second master devices at a time. 
     In embodiments of the present invention the dual porting apparatus  202  is implemented as an application specific integrated circuit (ASIC). 
     Referring generally to  FIG. 3 , in an alternative embodiment a dual porting apparatus  302  may be capable of being switched between the first and the second serial master devices through control signals sent from an external source, such as a SATA master device. 
     It is believed that the D UAL  P ORTING  S ERIAL  ATA D ISK  D RIVES  F OR  F AULT  T OLERANT  A PPLICATIONS  of the present invention and many of its attendant advantages will be understood by the forgoing 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.