Technical data

Tuning Techniques
2.2 Tuning Server Applications
There are no limitations on a server’s ability to handle millions of TCP
connections if memory resources are available to service the connections. If
memory is insufficient, the server will reject new connection requests until
memory is available. Use the netstat -m command to monitor the memory
that is currently being used by the network subsystem. See Section 1.2.4 for
information about displaying memory statistics.
2.2.2 Logging IP Addresses
If your server application logs client host names, the application software may
force the system to perform a reverse DNS lookup to obtain the client’s host
name. Reverse DNS lookups are time-intensive and can cause performance
problems on servers with many clients.
Many applications can be modified to log client IP addresses instead of client host
names. Logging IP addresses instead of host names may significantly improve
the efficiency of the server. Consult the documentation provided by the server
software vendor to determine how to disable the logging of client host names.
For example, you can obtain information about modifying Apache HTTP Server
software from the Apache HTTP Server documentation site.
2.2.3 Increasing the Auxiliary Server Connection Limit
The auxiliary server handles a limited number of service invocations in a one-
minute period of time. The default is a maximum of 500 connection requests. If
the number of requests exceeds this limit, the auxiliary server will not accept
additional requests for that service.
If your server receives more than eight requests per second for a service that is
spawned by the auxiliary server (for example, POP-3, FTP, and SMTP servers),
increase the default connection request limit. You can check the service’s
log file to determine if a service has been shut down. For example, the file
SYS$SYSDEVICE:[TCPIP$POP]TCPIP$POP_RUN.LOG will contain information
about the POP service.
Because the auxiliary server does not spawn any known HTTP server, the
connection request limit does not affect HTTP service.
2.2.4 Increasing the Maximum Number of BG Devices
You can configure TCP/IP Services to create more than 10,000 devices. This is
useful if the system is a web server.
The net subsystem attributes the provide information about allow you to modify
the way TCP/IP Services handles BG devices are described in Table 2–5.
Table 2–5 net Subsystem Attributes
Attribute Description
ovms_unit_count Informational attribute that shows the number of BG
devices that exist in the system. You cannot modify this
attribute.
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