DCE Application Programming Guide

Application Design Considerations

HP NonStop DCE Application Programming Guide—429551-003

2-9

Using a Fault-Tolerant Backing Store

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Note that HP COBOL for NonStop Systems compiler is located as follows:

The TNS version is located at /bin/cobol

The TNS/R version is located at /usr/bin/nmcobol.

The TNS/E version is located at /usr/bin/ecobol.

Each version supports different compilation and linking options. For more

information, see the appropriate cobol(1), nmcobol(1), and ecobol(1)

reference pages either online or in the Open System Services Shell and

Utilities Reference Manual.

Using a Fault-Tolerant Backing Store

Applications written for NonStop DCE can increase their fault-tolerance by opening the

backing store using a special value (db_c_use_nonstop) for the flags parameter

of the dbc_db_open() function. Using that flags value opens the backing store as

an OSS file with the file type S_NONSTOP.

Files with the file type S_NONSTOP are protected by disk process checkpointing and

are unlikely to lose data if a processor failure occurs. However, files with this file type

can affect performance in these ways:

•

Return from a write operation does not occur until the data checkpoint is

completed. This delay can affect thread timings.

•

OSS file-system caching is disabled for write operations on the file, which also

slows processing.

An application that performs a fault-tolerant backing-store open is using an extension

to DCE and therefore is less portable.

For more information about the flags parameter, see the dbc_db_open(3)

reference page online. For more information about the file type S_NONSTOP, see the

open(2) reference page either online or in the Open System Services System Calls

Reference Manual.