Self-healing fibre channel link

1. A method for verifying the integrity of a communication link, the method comprising,

detecting, during normal operation of a communication link, a condition indicative of a high failure rate (HFR) on the communication link;

placing the communication link in an HFR state as a result of the condition, wherein placing the communication link in HFR state comprises suspending transmission of real I/Os over the communication link while the communication link is in HFR state;

repeatedly transmitting test I/Os over the communication link while the communication link is in HFR state, wherein repeatedly transmitting test I/Os over the communication link comprises receiving a plurality of real I/Os for transmission over the communication link and, for each real I/O that is received, rejecting the real I/O and transmitting instead a test I/O over the communication link; and

automatically exiting HFR state and resuming normal operation on the communication link once at least one of the following has occurred: a selected number of test I/Os have been successfully transmitted over the communication link, and a number of test I/Os have been successfully transmitted over the communication link for a selected amount of time.

2. The method of claim 1 , wherein repeatedly transmitting test I/Os over the communication link comprises repeatedly performing the following:

generating a test I/O for transmission over the communication link;

marking the test I/O with an indicator indicating that the test I/O is for testing purposes;

sending the test I/O over the communication link; and

waiting for an acknowledgement that the test I/O was successfully transmitted over the communication link.

3. The method of claim 1 , wherein the communication link is a fibre channel communication link.

4. The method of claim 1 , wherein repeatedly transmitting test I/Os over the communication link comprises rejecting real I/Os that would normally be transmitted over the communication link.

5. The method of claim 1 , wherein the test I/Os contain test data as opposed to real data.

6. The method of claim 1 , wherein, prior to repeatedly transmitting test I/Os over the communication link, a preliminary test is performed on the communication link to determine if conditions on the communication link are suitable for transmitting the test I/Os.

7. The method of claim 1 , wherein transmitting test I/Os over the communication link comprises transmitting the test I/Os over the communication link at a rate that is substantially the same as a customer's transmission rate.

8. The method of claim 1 , wherein the selected number of test I/Os are a selected number of consecutive test I/Os.

9. A system for verifying the integrity of a communication link, the system comprising,

a first adapter to detect, during normal operation of a communication link, a condition indicative of a high failure rate (HFR) on the communication link;

the first adapter further configured to place the communication link in an HFR state as a result of the condition, wherein placing the communication link in HFR state comprises suspending transmission of real I/Os over the communication link while the communication link is in HFR state;

the first adapter further configured to repeatedly transmit test I/Os to a second adapter over the communication link while the communication link is in HFR state, such that for each real I/O that is received by the first adapter for communication over the communication link, the first adapter rejects the real I/O and instead transmits a test I/O over the communication link; and

the first adapter further configured to automatically exit HFR state and resume normal operation on the communication link once at least one of the following has occurred: a selected number of test I/Os have been successfully transmitted over the communication link, and a number of test I/Os have been successfully transmitted over the communication link for a selected amount of time.

10. The system of claim 9 , wherein the first adapter is configured to repeatedly perform the following:

generate a test I/O for transmission over the communication link;

mark the test I/O with an indicator indicating that the test I/O is for testing purposes;

send the test I/O to the second adapter over the communication link; and

wait for an acknowledgement from the second adapter that the test I/O was successfully transmitted over the communication link.

11. The system of claim 9 , wherein the communication link is a fibre channel communication link.

12. The system of claim 9 , wherein the test I/Os contain test data as opposed to real data.

13. The system of claim 9 , wherein the first adapter is further configured to perform a preliminary test on the communication link to determine if conditions on the communication link are suitable for transmitting the test I/Os.

14. The system of claim 9 , wherein the first adapter is configured to transmit the test I/Os over the communication link at a rate that is substantially the same as a customer's transmission rate.

15. The system of claim 9 , wherein the selected number of test I/Os are a selected number of consecutive test I/Os.

16. An apparatus for verifying the integrity of a communication link, the apparatus comprising,

a detection module to detect, during normal operation of a communication link, a condition indicative of a high failure rate (HFR) on the communication link;

a state module to place the communication link in an HFR state as a result of the condition, wherein placing the communication link in HFR state comprises suspending transmission of real I/Os over the communication link while the communication link is in HFR state;

a test module to repeatedly transmit test I/Os over the communication link while the communication link is in HFR state, such that for each real I/O that is received by the test module for communication over the communication link, the test module rejects the real I/O and instead transmits a test I/O over the communication link; and

an exit module configured to automatically exit HFR state and resume normal operation once at least one of the following has occurred: a selected number of test I/Os have been successfully transmitted over the communication link, and a number of test I/Os have been successfully transmitted over the communication link for a selected amount of time.

17. The apparatus of claim 16 , wherein the test module is configured to repeatedly perform the following:

generate a test I/O for transmission over the communication link;

mark the test I/O with an indicator indicating that the test I/O is for testing purposes;

send the test I/O over the communication link; and

wait for an acknowledgement that the test I/O was successfully transmitted over the communication link.

18. The apparatus of claim 16 , wherein the communication link is a fibre channel communication link.

19. The apparatus of claim 16 , wherein the test I/Os contain test data as opposed to real data.

20. The apparatus of claim 16 , further comprising a preliminary test module to perform a preliminary test on the communication link to determine if conditions on the communication link are suitable for transmitting the test I/Os.

21. The apparatus of claim 16 , wherein the test module is configured to transmit the test I/Os over the communication link at a rate that is substantially the same as a customer's transmission rate.

22. A computer program product to verify the integrity of a communication link, the computer program product comprising a non-transitory computer-readable storage medium having computer-usable program code embodied therein, the computer-usable program code comprising:

computer-usable program code to detect, during normal operation of a communication link, a condition indicative of a high failure rate (HFR) on the communication link;

computer-usable program code to place the communication link in an HFR state as a result of the condition, wherein placing the communication link in HFR state comprises suspending transmission of real I/Os over the communication link while the communication link is in HFR state;

computer-usable program code to repeatedly transmit test I/Os over the communication link while the communication link is in HFR state, wherein repeatedly transmitting test I/Os over the communication link comprises receiving a plurality of real I/Os for transmission over the communication link and, for each real I/O that is received, rejecting the real I/O and transmitting instead a test I/O over the communication link; and

computer-usable program code to automatically exit HFR state and resume normal operation once at least one of the following has occurred: a selected number of test I/Os have been successfully transmitted over the communication link, and a number of test I/Os have been successfully transmitted over the communication link for a selected amount of time.