OpenTP1 uses the UNIX message exchange functions (inter-process communication functionality enabled by system calls issued by the msgsnd and msgrcv functions) to input and output schedules of user servers, input and output performance verification trace data, and input journal data to and output journal data from journal files.

The following table shows how to estimate the size of each resource used by OpenTP1. For details about the system parameters, see the Release Notes and OS documentation.

Resource	Archive source node	Archive node
Number of message IDs	Number of dispersions x JDUAL + SVMAX + PRFNUM + 7 When using multiple OpenTP1 installations, multiply the result by the number of OpenTP1 environments.
Size of one message	56 bytes	56 bytes
Total number of bytes in the maximum queued message per message ID	Larger of the values determined from formulas A and B: Formula A 56 x number of file groups for system journal files x number of dispersions x JDUAL Formula B (PROC + maximum number of service requests that are simultaneously generated for one service group + number of server processes that simultaneously end abnormally + 4) x 56	56 x number of file groups for archive journal files x number of dispersions x JDUAL
Maximum number of queued OpenTP1 messages	(PROC x 2 + a + 2 + PRFNUM x 8) + number of server processes that terminate abnormally simultaneously When using multiple OpenTP1 installations, multiply the result by the number of OpenTP1 environments.	Number of file groups for archive journal files x number of dispersions x JDUAL + 19

Legend:

Number of dispersions: Value of the jnl_max_file_dispersion operand in the system journal service definition or the archive journal service definition

SVMAX: Value specified in the scd_server_count operand in the schedule service definition

PRFNUM: 9 when Y is specified in the prf_trace operand in the system common definition; 0 when N is specified in the prf_trace operand in the system common definition

JDUAL: 2 when Y is specified in the jnl_dual operand in the system journal service definition; 1 when N is specified in the jnl_dual operand in the system journal service definition

r: Number of resource groups specified in the -a option of the jnldfsv definition command in the global archive journal service definition

PROC: 1 when Y is specified in the prc_recovery_resident operand in the process service definition; number of user servers to be started when N is specified in the prc_recovery_resident operand in the process service definition

a: Maximum number of service requests that can be generated for OpenTP1 concurrently = (maximum number of concurrently generated service requests x number of SPPs) + (number of file groups for system journal files x number of dispersions x JDUAL)