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file descriptors - Setting the AIX nofiles - file descriptors

Technote (troubleshooting)

Problem(Abstract)

ulimit -Hn and ulimit -Sn outputs hard and soft nofiles(file descriptors),which is related to sockets available to the operating system and applications

Cause

When you are seeing out of thread related issues.

Resolving the problem

AIX:
ulimit -a outputs the following:
time(seconds) unlimited
file(blocks) 2097151
data(kbytes) 131072
stack(kbytes) 32768
memory(kbytes) 32768
coredump(blocks) 2097151
nofiles(descriptors) 2000 (hard limit max is unlimited, which is governed by OPEN_MAX)
NOTE: The hard limit must at least equal the soft limit before the soft limit
Can be changed.
The file that must be altered is the /etc/security/limits file and must be change by root.
fsize = 2097151
core = 2097151
cpu = -1
data = 262144
rss = 65536
stack = 65536
nofiles = 2000

NOTE: The setting can be done as default or by user, separate stanzas for the chosen method is required
To make it effective two methods can be used.
1. kill –1 <inetd process id> Process id can be acquired with the following command <ps –ef | grep inetd> or refresh inetd
2.reboot.

NOTE: Many Internet services are identified using a standard port number, the so-called well-known port numbers. For example, remote logins with TELNET are established using port 23. Mail delivery uses port 25. File transfers are done with ports 20 and 21. Any TCP connection request targeted at one of these well-known port numbers is understood to be for a particular service. For example, establishing a TELNET session to a remote host only requires a hostname lookup to find the remote IP address, then a connection to that host's port 23.

On UNIX systems, a program called Inetd maintains passive sockets on a variety of these well-known ports. When a new connection is created, inetd starts a program to handle the connection, based upon a configuration table. This way, one program can handle incoming connections for a variety of services. inetd only runs server programs as they are needed, and will spawn multiple server programs to service multiple network connections. inetd works best for network services with fairly long duration, so the extra startup overhead becomes negligible.

Product Alias/Synonym

AIX
Framework
FW
5698fra00

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Document information


Product categories:

	Software

	Systems and Asset Management

	Job Scheduling

	IBM Tivoli Management Framework


Operating system(s):
	AIX

Software version:
	All Versions

Reference #:
	1164221

IBM Group:
	Software Group

Modified date:
	2010-01-29

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