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Starting and Setting Up RTR
2.8 RTR ACP Virtual Memory Sizing
• Add the size of all messages
2. For each transaction router:
• Allow one Kbyte for each active transaction
3. For each back end:
• Allow one Kbyte per active transaction
• Allow fifty bytes for each message of a transaction
• Add the size of all replies
The total of all the contributions listed will yield an estimate of the likely virtual
memory requirements of the RTR ACP. A generous additional safety factor should
be applied as a final element to the total of virtual memory sizing. It is better to
grant the RTR ACP resource limits exceeding its real requirements than to risk
loss of service in a production environment as a result of insufficient resource
allocation. The total result should be divided by the virtual memory size in pages
to obtain the final virtual memory requirement. Process memory and page file
quotas should be set to accommodate as least this much memory.
Process quotas are controlled by qualifiers to the START RTR command. START
RTR accepts both links and application processes as qualifiers which can be
used to specify the expected number of links and application processes in the
configuration. The values supplied are used to calculate reasonable and safe
minimum values for the following RTR ACP process quotas:
• ASTLM
• BIOLM
• DIOLM
• FILLM
• PGFLQUOTA
Both /LINKS and /PROCESSES have high default values:
• The default value for /LINKS is now 512—This value is high but is chosen
to protect RTR routers against a failover where the number of front ends
is large and the number of surviving routers is small. The maximum value
for /LINKS is 1200 which is unchanged from earlier versions of RTR on
OpenVMS.
• The default value for /PROCESSES is 64— This value is large for front end
and router nodes but is sized for back ends hosting applications. Back ends
with complex applications may have to set this higher. The maximum value
for /PROCESSES is the OpenVMS allowed maximum. Warning messages
are generated if the requested (or default) memory quotas conflict with the
system-wide WSMAX parameter, or if the calculated or specified page file
quota is greater than the remaining free page file space.
• The default values for /LINK and /PROCESSES require a large page file.
RTR issues a warning if insufficient free space remains in the page file to
accommodate RTR, so choose values appropriate for your configuration.
Starting and Setting Up RTR 2–11