Communication apparatus and program provided with failure determining method and function

1. A method of determining a failure in an information system, the system including a transmission apparatus to transmit control information and a reception apparatus connected to the transmission apparatus in such a manner as to enable information to be transmitted and received, the reception apparatus to receive the control information and to transmit response information to the received control information, comprising:

obtaining, as a first clock time, a clock time of the most recently transmitted control information if the response information to the control information cannot be obtained within a predetermined time period;

obtaining, as a second clock time, a later one of a clock time of the response information most recently transmitted by the reception apparatus and a clock time of the control information most recently received by the reception apparatus; and

determining a failure location based on A) a type of control information indicating whether control information is transmitted control information or received control information and B) a before/after relationship of the first clock time and the second clock time.

2. The method of determining a failure of claim 1 , wherein the determining the failure location comprises:

determining that the failure location does not exist at least in the transmission apparatus if the first clock time is equal to or earlier than the second clock time, whereas the transmission apparatus decides that the failure location does not exist at least in the reception apparatus if the first clock time is later than the second clock time.

3. The method of determining a failure of claim 1 , wherein

the transmission apparatus is a server;

the reception apparatus is a storage;

and the control information is an input-output instruction to data stored in the storage.

4. The method of determining a failure of claim 3 , wherein

the transmission apparatus and the reception apparatus are connected to each other via a fiber channel;

the control information and the response information are split for transmission and reception into a plurality of frames in accordance with a fiber channel protocol;

the first clock time is a clock time when the server most recently transmits the frame; and

the second clock time is later one of a clock time when the storage most recently transmits the frame and a clock time when the storage most recently receives the frame.

5. A transmission apparatus in an information system including the transmission apparatus for transmitting control information and a reception apparatus connected to the transmission apparatus in such a manner as to enable information to be transmitted and received for receiving the control information, the reception apparatus transmitting response information to the received control information, the transmission apparatus comprising:

a first acquisition unit to obtain, as a first clock time, a clock time of the most recently transmitted control information if the response information to the control information cannot be obtained within a predetermined time period;

a second acquisition unit to obtain, as a second clock time, a later one of a clock time of the response information most recently transmitted by the reception apparatus and a clock time of the control information most recently received by the reception apparatus; and

a determination unit to determine a failure location based on A) a type of control information indicating whether control information is transmitted control information or received control information and B) a before/after relationship of the first clock time and the second clock time.

6. The transmission apparatus of claim 5 , wherein the determination unit to decide that the failure location does not exist at least in the transmission apparatus if the first clock time is equal to or earlier than the second clock time, whereas the determination unit is further to decide that the failure location does not exist at least in the reception apparatus if the first clock time is later than the second clock time.

7. The transmission apparatus of claim 5 , wherein

the transmission apparatus is a server;

the reception apparatus is a storage; and

the control information is an input-output instruction to data stored in the storage.

8. The transmission apparatus of claim 7 , wherein

the transmission apparatus and the reception apparatus are connected to each other via a fiber channel, wherein the control information and the response information are split for transmission and reception into a plurality of frames in accordance with a fiber channel protocol;

the first clock time is a clock time when the server most recently transmits the frame; and

the second clock time is later one of a clock time when the storage most recently transmits the frame and a clock time when the storage most recently receives the frame.

9. A computer readable medium on which is encoded a program to drive a transmission apparatus in an information system, the system including the transmission apparatus to transmit control information and a reception apparatus connected to the transmission apparatus in a manner allowing information transmission and reception, the reception apparatus to receive the control information and to transmit response information to the received control information, the encoded program including code executed by a computerized system for:

obtaining, as a first clock time, a clock time of the most recently transmitted control information if the response information to the control information cannot be obtained within a predetermined time period;

obtaining, as a second clock time, a later one of a clock time of the response information most recently transmitted by the reception apparatus and a clock time of the control information most recently received by the reception apparatus; and

determining a failure location based on A) a type of control information indicating whether control information is transmitted control information or received control information and B) a before/after relationship of the first clock time and the second clock time.

10. The computer readable medium of claim 9 , wherein the code for determining the failure location includes code that decides that the failure location does not exist at least in the transmission apparatus if the first clock time is equal to or earlier than the second clock time, whereas it is decided that the failure location does not exist at least in the reception apparatus if the first clock time is later than the second clock time.

11. The computer readable medium of claim 9 , wherein

the transmission apparatus is a server;

the reception apparatus is a storage; and

the control information is an input-output instruction to data stored in the storage.

12. The computer readable medium of claim 11 , wherein

the transmission apparatus and the reception apparatus are connected to each other via a fiber channel;

the control information and the response information are split for transmission and reception into a plurality of frames in accordance with a fiber channel protocol;

the first clock time is a clock time when the server most recently transmits the frame; and

the second clock time is later one of a clock time when the storage most recently transmits the frame and a clock time when the storage most recently receives the frame.