Loop initialization procedure exception handling for fibre channel transmissions

• US 6,584,511 B1
• Filed: 03/24/2000
• Issued: 06/24/2003
• Est. Priority Date: 03/24/2000
• Status: Expired due to Term

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: McDonald, Kathryn Ann, Jacobs, Willis Lloyd, Marsh, Ralph Ernest III
• Primary Examiner(s): Gaffin, Jeffrey
• Assistant Examiner(s): Nguyen, Mike
• Application Number:
  US09/534,519
• Time in Patent Office: 1,187 Days
• Field of Search: 710/36, 710/48, 710/49, 710/50, 710/5-7, 710/260-269, 710/15
• US Class Current: 710/5
• CPC Class Codes: H04B 10/50 Transmitters

Abstract

A fiber optic channel loop provides a transmission path between a computer platform and a multiple number of peripheral devices. When any change occurs in the number of connected peripheral devices or their operation status, then Fiber Channel loop is interrupted so to disable ongoing Input/Output operations to a targeted peripheral device. When this interruption is sensed, the Master Control Program of the platform will institute corrective measures to re-originate any interrupted I/O operations.

Claims

1. A method for handling exceptions to any I/O operation between a computer platform operating under a Master Control Program, and selected target peripheral unit, comprising the steps of:

(a) identifying a target peripheral unit to be sent a data package of X selected bytes;

(b) organizing by said Master Control Program, an I/O Command Packet with a selected Fibre Channel address and a buffer of data to be transmitted;

(c) transmitting said buffer of data to a channel manager unit (CMU);

(d) sending, by said CMU, of said data buffer to a selected Fibre Channel host bus adaptor (HBA) for conveyance to said Fibre Channel target peripheral device;

(e) sensing by said Fibre Channel HBA, when an interruption to data transmission has occurred because of a Loop Initialization Procedure which operates to send a non-completed I/O signal to said Master Control Program.

2. The method of claim 1 which further includes the step of:

(g) checking to see if I/O operations were indeed interrupted by a Loop Initialization Procedure (LIP);

(h) continuing normal I/O operations if no valid LIP occurred.

3. The method of claim 1 where step (e) includes the steps of:

(e1) sensing the occurrence of a LIP result indicating an exception event for the selected I/O operation;

(e2) checking the selected I/O command to verify that I/O is transferred.

4. The method of claim 3 wherein step (e2) includes the step of:

(e2a) retrying the selected I/O command operation if the I/O command did not transfer data.

5. The method of claim 3 wherein step (e2) includes the step of:

(e2b) returning the I/O command as lost and irrecoverable if the I/O command was in the process of transferring data.

6. The method of claim 1 wherein step (e) includes the steps of:

(ie) checking whether the I/O operation transmitted said buffer of data to said target peripheral unit;

(iie) retrying the I/O if the buffer of data did not reach said target peripheral unit.

7. The method of claim 1 wherein step (e) includes the step of:

(ae) instituting a special program designated HANDLEMAGTAPEEXCEPTION if the I/O operation did transfer any data of said buffer of data to said selected peripheral unit.

8. The method of claim 7 wherein step (ae) includes the steps of:

(ae1) checking to see if a LIP result signal indicated that the selected I/O operation was not completed;

(ae2) sensing whether the selected I/O command was recoverable;

(ae3) returning the I/O command if the I/O was transferring data to indicate that the I/O is not recoverable.

9. The method of claim 8 wherein step (ae2) includes the step of:

(ae2i) retrying the I/O if the I/O command did not transfer data.

10. A system for handling the notification of interrupted I/O operations between a computer platform and a selected target unit among multiple peripheral units connected to a Fibre Channel Loop comprising:

(a) Master Control Program means to initiate an I/O data transfer command between a computer platform and a group of target peripheral units connected to a Fibre Optic Channel Loop;

(b) fibre optic cable means forming an arbitrated transmission loop to said group of multiple peripheral units;

(c) means to sense an exception condition signal in the I/O command during data transfer operations;

(d) means for initiating a new Loop Initialization Procedure (LIP) to re-organize the identity numbers of said group of peripheral units when a change has occurred in the number of peripheral units connected to said Fibre Channel Loop for completing incomplete I/O data transfers when possible;

(e) means for re-trying the transfer of data on those previous incomplete I/O data transfer commands.

13. The system of claim 10 wherein said LIP indicates those exception condition I/O operations which are recoverable.

11. A system of handling the notification of interrupted I/O operations between a computer platform means and a target peripheral unit utilizing a Fibre Channel optical cable comprising:

(a) computer platform means for setting-up an I/O command for communication to multiple peripheral units;

(b) Fibre Channel Host Bus Adaptor means for transferring a buffer of data from said platform to said target peripheral unit;

including

(b1) means for sensing any change in the Fibre Channel cable connections to said multiple peripheral units and for notifying said computer platform;

(c) means for re-identifying the new channel cable connection arrangements of said multiple peripheral units via signals from said Fibre Channel Host Bus Adaptor;

(d) means for re-transmitting any incomplete I/O commands to completion or sensing those interrupted I/O commands which are not recoverable.

12. The system of claim 11 wherein said computer platform means includes:

(a1) Master Control Program means for initiating and controlling I/O operations;

(a2) I/O Control Block means for identifying a target peripheral unit and including;

(a2a) a buffer unit for holding data of X bytes;

(a3) a Command Packet means for holding (i) the target device address, (ii) buffer data retrieved from memory, (iii) Input/Output Result Descriptor information;

(a4) an Input/Output Module which communicates with a Channel Manager Unit (CMU 15);

(a5) said CMU for communicating to up to four different channels of which at least one of them is a Fibre Channel Host Bus Adapter;

(a6) Fibre Channel Host Bus Adapter means (16) for conveying data to Hub means for Fibre Channel transmissions to a selected target device of multiple peripheral units.

14. In a computer platform wherein a Master Control Program organizes an I/O Control Block to utilize an I/O Module for designating a command packet to a Channel Manager Unit to convey data from memory to a Fibre Channel Host Bus Adaptor, a method for detecting a Loop Initialization Procedure for handling data transfers to and from selected peripheral units comprising the steps of:

(a) sensing the identity of each peripheral device connected to a Fibre Optic loop from a hub connected to said Fiber Channel Host Bus Adaptor;

(b) initiating a data transfer operation from said Memory to a selected peripheral unit by said Master Control Program.

15. The method of claim 14 which includes the steps of:

(c) receiving, by said Fibre Channel Host Bus Adaptor, of an incomplete I/O operation signal indicating a different status of the peripheral units in said Fibre Channel Loop;

(d) notifying said Master Control Program of said incomplete I/O operation;

(e) re-trying the transfer of data to selected peripheral units after the earlier incomplete I/O operation.

16. The method of claim 15 wherein step (c) includes the step of:

(c1) sending of a Result Descriptor message from said Fibre Channel Host Bus Adaptor to said Master Control Program.

17. A platform utilizing a Master Control Program which manages data transmissions to and from selected peripheral units comprising:

(a) Master Control Program means for enabling data transmission to and receiving data from selected peripheral units;

(b) I/O Control block means for selecting destination addresses of peripherals and pointers to data in memory to selected peripherals;

(c) an I/O Module means for utilizing said addresses and memory data into a command packet for conveyance to a Channel Manager Unit;

(d) a Fibre Channel Host Bus Adaptor means for conveying said memory data to a selected peripheral and for receiving signals as to non-completion of the data transfer;

(e) means using said Channel Manager and I/O Module to signal non-complete to said Master Control Program.

18. The platform of claim 17 which includes:

(a) means to re-try data transmission for those incomplete data transmission attempts priorly attempted.

19. A method for handling exceptions to I/O operations between a computer platform operating under a Master Control Program (MCP) and selected target peripheral units comprising the steps of:

(a) initiating a selected data transfer operation using an I/O Control Block by said MCP via an I/O Module, a Command Packet, a Channel Manager Unit (CMU) and Fibre Channel Host Bus Adaptor;

(b) transmitting by said Fibre Channel Host Bus Adaptor, data transfer operation via a Fibre Channel Loop to selected target peripheral units;

(c) sensing when a peripheral device has been removed from, or added to said Fibre Channel Loop and sending a Loop Initialization Procedure exception signal to said MCP;

(d) determining by said MCP, that said data transfer operation Loop Initialization Procedure occurred in the middle of an I/O transfer operation;

(e) terminating, by said MCP, of said I/O transfer operations.

20. The method of claim 19 wherein step (d) includes the steps of:

(d1) determining, by said MCP, that said data transfer operation Loop Initialization Procedure indicated that no data was transferred;

(d2) retrying of said incomplete data transfer operation by said MCP.

21. The method of claim 19 wherein step (d) further includes the steps of:

(d3) determining, by said MCP, that a Loop Initialization Procedure exception signal occurred in the middle of a tape I/O operation;

(d4) canceling, by said MCP, of said incomplete I/O data transfer operation.