Abstract:
An input/output device and a method of setting up identification information for an input/output device, to confirm which slot of which device enclosure each unit is mounted in, within a short time, from a map, and execute quick access to the unit. A unit mounted on a device enclosure is assigned a slot identification information that does not overlap with that for another unit in the device enclosure, each device enclosure is assigned device enclosure identification information that does not overlap with that for another device enclosure, and a table is formed using unit identification information, which consists of the slot identification and the device enclosure identification information, and which does not overlap with that for another unit in the device, thus allowing a unit in the device to be specified.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to an input/output device comprising: a plurality of device enclosures; a plurality of units that are mounted on said multiple device enclosures; a table indicating a correspondence between an access object device specified by an external device and one of said multiple units; and a control unit that logically connects the external device with the corresponding unit based on said table; and a method of setting up identification information in such an input/output device. 
   2. Description of the Related Art 
   A type of device has been available having a rack loaded with a multiple of device enclosures, each of which is mounted with a multiple of hard disk drives (“HDD”). It is so constituted in such a device that a discrete slot identification (“ID”) code is assigned to each HDD mounted in each slot, 1 through n, provided in each enclosure, and a map (AL-PA map) is formed based on device enclosures&#39; IDs and slot IDs read from hard disk drives each time when the power in turned on, so that a particular HDD can be accessed referring to said map when it is requested by a host computer. 
   A control device has also been disclosed, which consists of a plurality of printed circuit boards each equipped with a transmission LSI as an address function to identify which board is located where, and acquires the address of each printed circuit board with the help of said transmission LSI (Document 1). 
   A technology has also been disclosed wherein a plurality of drive units are connected to each of a plurality of mother boards assigning a discrete serial number to each drive unit, said discrete serial number comprising specific upper bits pre-assigned to each mother board (Document 2). 
   Document 1) Japanese Utility Model Gazette No. 2570074, especially FIG. 1 and [0006] of that. 
   Document 2) Japanese Patent Publication No. 04-137258, especially FIG. 1 and the Means of Solving the Problems, Specification of that. 
   Thus, although the slot ID of an HDD mounted on one of the slots, 1 through n, in a device enclosure can be uniquely defined, it is not unique when other device enclosures are considered, so that it is necessary to form a map obtaining the ID of the particular device enclosure and the slot ID of the HDD mounted in said device enclosure each time when the power is turned on in order to access the particular HDD (a unique address (physical location) corresponding to the HDD) in response to an access request received from the host computer, which causes problems such that it takes a lot of time to form such a map. 
   The method disclosed by the abovementioned Document 1 also has a problem that it causes a necessity to mount a transmission LSI. 
   The method disclosed by the abovementioned Document 2 also has a problem that it causes a necessity of presetting discrete serial number of each mother board. 
   SUMMARY OF THE INVENTION 
   In order to solve these problems, the present invention intends to set a unique slot ID (e.g., the lower 4 bits) for each unit (e.g., HDD) mounted on a device enclosure and a unique ID (e.g., the upper 3 bits) for each device enclosure each time when the power is turned on, form a map based on the slot ID of the unit after setting, access a particular unit (e.g., HDD) based on said map when an access is requested, and consequently realizing a fast access to a unit (e.g., HDD) by quickly forming a map, checking which slot of which device enclosure the particular unit is located. 
   The means of solving the problems will be described below referring to  FIG. 1 . 
   In  FIG. 1 , a rack  1  is a rack for storing a control enclosure (CE)  2  and a plurality of device enclosures (DE)  3 . 
   Control enclosure  2  is for providing an overall control for the entire system. 
   A device enclosure  3  is for carrying a plurality of units, or HDD  4 , and comprises HD  4 , a back panel (BP)  5 , and a port bypass circuit unit (PBCU)  7 . 
   HDD  4  are hard disk drives and an example of the unit. 
   Back panel (BP)  5  is for carrying a plurality of HDD  4  and holds the first ID (the lower 4 bits which are the fixed value for HDD  4 ) that constitutes HDD  4  slot ID. 
   Port bypass circuit unit (PBCU)  7  holds the second ID (e.g., the upper 3 bits) unique to each device enclosure  3 . 
   Next, the actions will be described. 
   It is constituted in such a way that a plurality of device enclosures  3  are installed in rack  1 , a plurality of HDD  4 , or units, are mounted on back panel  5  of each device enclosure  3 , ID (device enclosure identification information) That represents each device enclosure  3  is set up, and a map (table) is formed after setting up said ID by converting slot ID, which consist of unit identification information (slot identification information) acquired from HDD  4 , or units, within each device enclosure  3  and device enclosure identification information, into a physical location or an address to be accessed. A particular unit is accessed based on the map (table) when an access request is received from the host computer (or external device). 
   The unit identification information (slot identification information) and the device enclosure identification information both expressed in a certain number of bits are combined to form the slot ID. 
   Therefore, by setting up a unique slot ID (e.g., the lower 4 bits) for each unit, e.g., HDD  4 , mounted on a device enclosure  3  and a unique ID (e.g., the upper 3 bit) (or each device enclosure  3  each time when the power is turned on, forming a map (table) based on the slot ID of the unit or HDD  4  after the setting, accessing a particular unit or HDD based on said map when an access is requested, it is possible to realize a fast access to a unit or HDD  4  by quickly forming a map, checking which slot of which device enclosure  3  the particular unit is located. 
   As can be seen from The above, as a result of constituting the system In such a way as to set up a unique slot ID (e.g., the lower 4 bit) for each unit, e.g., HDD  4 , mounted on a device enclosure  3  and a unique ID (e.g., the upper 3 bits) for each device enclosure  3  each time when the power is turned on, form a map based on the slot ID of the unit or HDD  4  after the setting, and access a particular unit or HDD based on said map when an access is requested, it is possible to realize a fast access to a unit or HDD  4  by quickly forming a map, checking which slot of which device enclosure  3  the particular unit is located. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a system constitution drawing of the invention. 
       FIG. 2  is a descriptive drawing (slot ID) of the invention. 
       FIG. 3  is a flowchart for describing the operation (during the setup) of the invention. 
       FIG. 4  is a detailed flowchart (for the forming of FC-MAP) of the invention. 
       FIG. 5  is an example table of the invention. 
       FIG. 6  is an example map table of the invention. 
       FIG. 7  is a flowchart for describing the operation (during the access) of the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Next, a preferred embodiment of the invention and its action will be described in sequence referring to  FIG. 1  through  FIG. 7 . 
     FIG. 1  shows a system constitutional diagram of a preferred embodiment of the invention. 
   In  FIG. 1 , a rack  1  stores a control enclosure (“CE”)  2  and a plurality of device enclosures (DE)  3 . 
   Control enclosure (CE)  2  provides an overall control of the entire system (refer to  FIG. 3 , etc.). 
   Device enclosure  3  is for carrying a plurality of units, or HDD,  4  and comprises, a back panel (“BP”)  5 , and a port bypass circuit unit (“PBCU”)  7 . 
   HDD  4  are hard disk drives and an example of a “unit” in the description). 
   Back panel (BP)  5  carries (or is connected with) a plurality of HDD  4  and comprises a register/memory  6  for holding the first ID (the lower 4 bits, which are a fixed values, for identifying HDD  4 ) and constitutes an HDD  4  slot ID. 
   Port bypass circuit unit (PBCU)  7  comprises a register/memory  8  for holding a unique second ID (e.g., the upper 3 bits) for each device enclosure  3  (refer to  FIG. 3  through  FIG. 6 ). 
     FIG. 2  shows a system constitutional diagram (i.e., a slot ID diagram) of a preferred embodiment of the invention. This shows that  15  HDD  4  are mounted on each of shelves DE 00 , DE 01 , . . . . and a slot ID is set up for each HDD  4 , consisting of a first ID (a fixed value for each HDD  4 , which consists of the lower 4 bits and is held by register/memory  6 ) and a second ID (a unique fixed value for each device enclosure  3 , which consists of the upper 3 bits and is held by register/memory  8 ). For example,
         The slot ID of the HDD  4  first from the left in DE 00  (device enclosure&#39;s ID =00) =0000000.   The slot ID of the HDD  4  second from the left in DE 00 =000 0001.   The slot ID of the HDD  4  third from the left in DE 00 =000 0010.   The slot ID of the HDD  4  fourth from left in DE 00 =000 0011.   The slot ID of the HDD  4  fifth from the left in DE 00 =000 0100.   The slot ID of the 15th HDD  4  from the left in DE 00 =000 0111. The slot ID (7 bits) is set up similarly for shelves DE 01 , DE 02 , . . . as shown.       
   By setting up a unique ID (second ID) for each DE  3  using the upper 3 bits of the 7 bits representing the slot ID of HDD  4  when, for example, the power is turned on and storing (writing) it in register/memory  8  of  FIG. 1  as described above, it is possible thereafter to read out the slot ID of HDD  4  consisting of 7 bits, obtain an AL-PA value referencing the table shown in  FIG. 5  as described later, set it up in the map ( FIG. 6 ), and access the particular HDD  4  based on said map in correspondence to an access request received from the host computer. This process will be described step by step in the following. 
     FIG. 3  is a flowchart (at the time of setup) for describing the action of the invention. 
   In  FIG. 3 , the power is turned on in the step S 1 . This turns on power to all devices stored in rack  1  including CE  2 , DE  3 , etc. in  FIG. 1 . 
   In the step S 2 , DE-ID is set up. In the step S 3 , the upper 3 bits of the slot ID are set up based on DE-ID. In the steps S 2  and S 3 , the aforementioned CE  2  sets up a unique ID for each DE (device enclosure)  3  on register/memory  8  in each PBCU  7  of DE  3  in  FIG. 1 , and sets up (writes) DE-ID (e.g., “000” for DE- 00 ) in the upper 3 bits of the slot ID of each HDD  4  in each DE  3 . This causes the following, which is also shown on the right side of the flowchart,
         DE 00 →0 0 0 X X X X   DE 01 →0 0 1 X X X X   . . . .   be set up for the slot ID for each DE  3 . The values of the lower 4 bits, which are shown here by X, 0 or 1, can be any four bit values, which represent the fixed values assigned to each HDD  4  (fixed values set up in register/memory  6  shown in  FIG. 1 ).       

   In the step S 4 , FC-MAP is formed. This process is to form a map shown in  FIG. 6  based on the slot ID established in the step S 3  referencing the table shown in  FIG. 5  in accordance with the flowchart shown in  FIG. 4  to be described later. 
   This makes it possible to form the map based on the slot ID for each HDD  4  (the upper 3 bits representing the device enclosure&#39;s ID and the lower 4 bits representing the particular HDD&#39;s ID) referencing the table shown in  FIG. 5  (in accordance with the flowchart shown in  FIG. 4  to be described later), once an arbitrary value to represent each device enclosure  3  is set up for the upper 3 bits of the slot ID consisting of 7 bits for each HDD  4  in each device enclosure  3 . 
     FIG. 4  is a flowchart (at the time of forming the FCMAP) for describing the details of the invention. 
   As shown in  FIG. 4 , the slot ID is acquired in the step S 11 . 
   In the step S 12 , SEL-ID is calculated based on the upper 3 bits and the lower 4 bits referencing the cell table. For example, if a slot ID=000 0000 is acquired from the first HDD from the left in DE 00  in the step S 11 , the value “00”, which is marked by {circle around (1)} in (a) SEL table  9  in  FIG. 5 , is acquired as the SEL-ID based on the upper 3 bits “000” and the lower 4 bits “0000.” 
   In the step S 13 , the AL-PA value is calculated based on the SEL-ID referencing an AL-PA table  10 . For example, the value “EF”, which is marked by {circle around (2)}, is calculated as an AL-PA value based on SEL-ID=00 acquired in the step S 12  referencing (b) AL-PA table  10  in  FIG. 5 . 
   In the step S 14 , the AL-PA value is judged whether it is overlapping. This is to Judge whether the AL-PA value calculated in the step S 13  is overlapping with other AL-PA values already calculated. If the answer is YES, it means it is overlapping, so that it is changed to an AL-PA value unique to the HDD in the step S 15  and the program then advances to the step S 16 . If the answer is NO in the step S 14 , the program advances to the step S 16 . 
   In the step S 16 , a judgment is made as to whether the steps S 11  through S 15  have been executed for all HDD slot ID. If the answer is YES, an FC-MAP table is prepared in the step S 17  and the process will be terminated. For example, in correspondence with the following, which is shown in the FC-MAP table of  FIG. 6 :
         DE (the upper 3 bits of the slot ID)=0 0 0   Slot ID (the lower 4 bits)=0 0 0 0
 
the AL-PA value “EF” calculated (or changed in the step S 15 ) in the step S 13  is set up.
       

   Thus, it becomes possible to calculate the AL-PA value based on the slot ID acquired from HDD  4  (slot ID consisting of the upper 3 bits and the lower 4 bits) referencing the table shown in  FIG. 5  and set it on the map (FC-MAP table shown in  FIG. 6 ). It also becomes possible to access a particular HDD when an access request is received from the host computer based on the AL-PA value (HDD&#39;s physical location/address) of said HDD referencing the map (FC-MAP table in  FIG. 6 ). 
     FIG. 5  shows an example table of the invention. 
     FIG. 5(   a ) shows an example of SEL table  9 . The columns here represent the upper 3 bits of the slot ID, while the rows represent the lower 4 bits of the slot ID. Each cell where a column and a row cross each other represents the SEL-ID in question. 
     FIG. 5(   b ) shows an example of AL-PA table  10 . The SEL-ID value represents the SEL-ID value calculated in (a) SEL table in  FIG. 5 , and the AL-PA value is the AL-PA value in question (HDD&#39;s physical location/address). 
   It becomes possible to calculate the AL-PA value from the slot ID (the upper 3 bits and the lower 4 bits) acquired from HDD  4  by referencing the above tables. 
     FIG. 6  shows an example map table  11  of the invention. FC-MAP table  11 , which is an example of map table  11 , consists of the AL-PA values calculated in correspondence to DE (the upper 3 bits of the slot ID) and the slot ID (the lower 4 bits that correspond to HDD&#39;s specific ID) referencing the table shown in  FIG. 5 . When an access request is received, the AL-PA value for the corresponding HDD can be retrieved referencing the FC-MAP table and an access can be made accordingly. 
     FIG. 7  is a flowchart (at the time of access) for describing the action of the invention. 
   CE  2  requests writing of data to DE 00  slot 00 in the step S 21  as shown in  FIG. 7 . 
   In the step S 22 , the data writing into the address EF is executed corresponding to the request. In this process, the AL-PA value=EF marked by {circle around (3)} in the FC-MAP table shown in  FIG. 6  is retrieved concerning the DE 00  slot 00 for which the data writing request was made in the step S 21 , and the data is written into said address EF. 
   In the step S 23 , a normal response from the HDD is received. 
   Thus it is possible to make an access to a corresponding HDD using the corresponding AL-PA value as the address referencing the aforementioned table in  FIG. 6  when an access request specifying DE 00  slot 00 and the like is received from CE  2 . 
   The present invention is not limited to the details of the above described preferred embodiments. The scope of the invention is defined by the appended claims and all changes and modifications as fall within the equivalence of the scope of the claims are therefore to be embraced by the invention.