JPH033054A - Method for preventing communication data from being missed - Google Patents

Abstract

PURPOSE:To prevent data from being missed due to the generation of an instantaneous stop by comparing the values of 1st and 2nd registers with each other, deciding whether a host system succeeds in data reception or not by means of firmware, and if the host system fails the data reception, informing the preceding receiving data to the host system again. CONSTITUTION:The 1st register A for increasing its contents immediately before the output of a data receiving request generated from an inter-host communication driver 4 after normally receiving data and the 2nd register B for increasing its contents immediately after deciding the normal reception of data by the firmware 1 are prepared, and prior to the start of data transmission/reception, '0' and '1' are respectively set up in the registers A, B. Immediately before starting the receiving operation of the firmware 1, the values of the two registers are compared with each other and data missing is decided in accordance with the coincidence/discrepancy of both the values. The discrepancy indicates data missing and the preceding receiving data are informed to the host system again. Thus, the generation of data missing an be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a prevention method for preventing communication data from being lost due to an instantaneous power failure (instantaneous power outage) of a host that is a receiving station in communication between hosts.

<Prior Art> The data receiving operation of conventional firmware in host-to-host communication will be explained as follows with reference to the block diagram of FIG.

■Data transfer with the other host begins.

■The DMA (Dl
(rect Mea + ory Access) transfer.

- When the DMA transfer ends normally, the other host is notified of the completion of data reception. At this point, the other host recognizes that the data transmission has ended normally.

(2) The inter-host communication firmware 1 notifies the channel adapter driver 3 of completion of data reception. The channel adapter driver 3 then calls the host-to-host communication driver 4, and the received data is processed by the host-to-host communication driver 4.

It is assumed here that the architecture of the host computer is as shown in FIG. That is, a central processing unit (abbreviated as CPU) 10 and memory 11 are connected by a CPU-memory bus 12, and an input/output card (referred to as I10 card) 13, which is a channel adapter, is connected to the bus 12. This channel adapter 13 and various input/output I10 cards (device adapters) 15a
, 15b, and 15c are connected by a channel bus 14.

In short, I10 between CPU and memory and for input/output devices
The architecture is such that each card has a separate bus system, and there is a channel adapter to control both.

<Problems to be Solved by the Invention> However, the following problems occur in such a host computer.

If an instantaneous power outage occurs in the host computer immediately after the above notification (■) is made and immediately before the channel adapter driver performs the reception operation, the channel adapter driver will respond to the I10 request being output to indicate that an instantaneous power outage has occurred. The I10 request is issued again. This is because the firmware assumes that the reception operation has failed due to the instantaneous power failure.

However, since data transfer between the firmware and the partner system has already been completed, data loss occurs.

The present invention has been made in view of these points, and its purpose is to prevent momentary power outages from occurring in a host computer where a driver for managing all system Ilo is interposed between a driver dedicated to inter-host communication and firmware. The objective is to provide a method for preventing data omission.

Means for Solving the Problems> The present invention for achieving the above objects provides a first method for communication between hosts. A second register is prepared, the first register is incremented after the host-to-host communication driver determines that data is received normally, and the second register is incremented after the host-to-host communication firmware determines that data is received normally. This 1st. The firmware determines whether the host system has successfully received data by comparing the values of the second register, and if the host system fails to receive data, it notifies the host system of the previous received data again. The feature is that data is prevented from being dropped.

Function> In the present invention, the first register A is incremented by the host-to-host communication driver immediately before outputting a data reception request issued after normal reception of data, and the first register A is incremented immediately after the host-to-host communication firmware determines that data has been received normally. A second register B is provided which increments the data, and register A is set to 0 and register B is set to 1 before starting data transmission/reception. Immediately before the firmware starts the reception operation, the values in the two registers are compared, and data loss is determined based on whether they match or do not match. If there is a mismatch, data is missing, and the host system is notified of the previously received data again.

By making the determination and re-notifying in this manner, data omission can be prevented.

<Example> The method of the present invention will be described in detail below with reference to the drawings. 1st
The figure is a block diagram of a method for preventing communication data loss according to the present invention. The difference from Figure 4 is the communication register 5.
(communication register A) and communication register 6 (communication register B) are prepared. Register A is accessed by the host-to-host communication driver 4, and register B is accessed by the host-to-host communication firmware 1. The host-to-host communication driver 4 increments register A immediately before outputting a data reception request (■ in the figure), and the host-to-host communication firmware 1 increments register B after completing data reception from the other host (■ in the figure). ). The host-to-host communication driver 4 does not increment the register A when a reception request is reissued due to an error as described in the conventional example.

As a result, at the stage (■) where the host-to-host communication firmware 1 compares registers A and B immediately before receiving data from the other host, it is determined whether the receive request from the host-to-host communication driver 4 is due to reissue due to an error. It is possible to determine whether or not the data is present, thereby making it possible to prevent data omission.

The method of the present invention will be explained in detail below using flowcharts.

First, after booting the system and before starting data transmission/reception, the host-to-host communication driver 4 sets register A to O, and the host-to-host communication firmware 1 sets register B to 1.

The reason why the values of the two registers are different by one is so that the firmware can compare the values and determine whether they match or do not match immediately before starting the reception operation.

A flowchart of data reception is shown in FIG. In the figure, related inter-host communication firmware 1,
The operation flows of the channel adapter driver 3 and the inter-host communication driver 4 are shown in parallel. In this case, if an instantaneous power failure occurs while the channel adapter driver 3 is outputting a data reception request (while setting a flag), the channel adapter driver 3 notifies the host-to-host communication driver 4. Inter-host communication driver 4
assumes that the reception operation has failed due to an instantaneous power outage and reissues the reception request. The operation flow is shown in FIG.

As shown in FIG. 3, register A is not incremented when a reception request is reissued due to an instantaneous power failure. On the other hand, register B is incremented by firmware when the reception operation is completed, as described in the conventional example. Therefore, the path shown in (b) in the flow of FIG. 2 is executed, and the received data can be passed to the driver.

If the reception operation itself in the firmware fails due to an instantaneous power failure, register B will not be incremented, so the second register will not be incremented.
In the flowchart of the figure, the path shown by (C) (this path is a normal data reception sequence) is executed.

<Effects of the Invention> As described above in detail, the present invention has the following effects.

(A) Data loss caused by instantaneous power outages can be prevented.

If there is a disturbance to be handled in the same way as an instantaneous power failure in the channel adapter driver, data loss can be prevented by taking similar measures.

(B) When applying the present invention, there is no need to change the conventional channel adapter driver. existing firmware,
The inter-host communication driver requires some modification, but
All it takes is a little modification.

[Brief explanation of drawings]

FIG. 1 is a block diagram related to the communication data loss prevention method of the present invention, FIGS. 2 and 3 are flowcharts for explaining the operation, FIG. 4 is a block diagram related to data reception using conventional firmware, and FIG. The figure shows the architecture of a host computer. 1... Firmware for communication between hosts 2... Buffer for reception 3... Driver for channel adapter 4... Driver for communication between hosts

Claims (1)

[Claims] A channel adapter connected to a CPU-memory bus to which a central processing unit and memory are connected connects to a plurality of device adapters via a channel bus that is separate from the CPU-memory bus. In a computer system architecture in which host-to-host communication is performed with the channel adapters controlling both buses, when data transfer with the other host begins, the host-to-host communication firmware uses the receive data specified by the host to DMA transfer is executed to the buffer area, and when the DMA transfer is completed successfully, the other host is notified of the completion of data reception.After that, when the channel adapter driver receives the notification of the completion of data reception, the driver for communication between the upper hosts is notified. In host-to-host communication in which the received data is processed by the host-to-host communication driver, the host-to-host communication driver increments the first register if the host-to-host communication driver determines that the data is received normally; If the host system firmware determines that the data has been successfully received, the host system increments the second register, and then compares the values of the first and second registers to determine whether the host system has successfully received the data. A communication data dropout prevention method comprising the steps of: reissuing a data reception request if data reception fails.