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Warning of Trace Data Lost

IP.com Disclosure Number: IPCOM000060238D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Clarke, K: AUTHOR [+2]

Abstract

A method to inform the operator of an IBM PC Network SNA 3270 Emulation Program that trace data may have been lost is described. The IBM PC Network SNA 3270 Emulation (PCN 3270) Program provides an online data trace function to trace SNA data. The trace function makes use of two buffers, buffer A and buffer B. The trace process starts with buffer A, filling it with trace data. When buffer A is full, the trace process switches to using buffer B, and initiates writing of buffer A to disk. It is possible that trace data may arrive at a time when buffer B is full, and buffer A is still waiting to be written to disk. In this case, the arriving trace data is discarded, and a way of notifying the operator of data lost is needed. For each record of SNA data that is stored in the trace buffers, a trace header byte is stored.

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Warning of Trace Data Lost

A method to inform the operator of an IBM PC Network SNA 3270 Emulation Program that trace data may have been lost is described. The IBM PC Network SNA 3270 Emulation (PCN 3270) Program provides an online data trace function to trace SNA data. The trace function makes use of two buffers, buffer A and buffer B. The trace process starts with buffer A, filling it with trace data. When buffer A is full, the trace process switches to using buffer B, and initiates writing of buffer A to disk. It is possible that trace data may arrive at a time when buffer B is full, and buffer A is still waiting to be written to disk. In this case, the arriving trace data is discarded, and a way of notifying the operator of data lost is needed. For each record of SNA data that is stored in the trace buffers, a trace header byte is stored. One bit of that byte is used to indicate that trace data was lost. That bit is set if trace data arrives when both buffer A and buffer B are filled and waiting to be written to disk. The trace header is stored with the next record that can be written into one of the buffers. It signals that previous trace data may have been lost. When the trace is completed, a trace analyzer decodes the information and flags the area where data was lost. Detecting the loss and storing the trace data lost indicator, makes it possible to warn the operator that the trace output is not complete.

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