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SRC (System Resource Controller) in AIX

 One of the unique facilities available on AIX is System Resource Controller (SRC). The SRC gives a set of commands that make it very easy for the system administrator to maintain and manage the subsystems and subservers running on your AIX system.

What is a subsystem ?

Subsystem is a set of related programs designed to perform one particular function. The subsystems can be sub divided into subservers(daemons).
SRC helps you to manage the whole subsystems and their respective subservers by creating subsystem groups. You can use SRC related commands to start/stop/refresh the subsystems and subservers.
In the example above, there is a subsystem group called tcpip. Under the subsystem group called tcpip you have a subsystem called inetd. Under the subsystem called inetd you have a subserver called telnet.
So to work with either the group called tcpip or the subsystem called inetd or the subserver called telnet, you need to use the SRC set of commands.
In other words, the SRC (System Resource Controller) is a process manager that is used to spawn, monitor and control services. Many of the standard Unix daemons are managed via this interface on AIX.
SRC does not have a persistent "service profile" and therefore does not comprehend persistence beyond the current boot. For this reason, it is necessary to find where the service is started and add or remove the startsrc (service start) command there. The most popular locations for this are rc.tcp and inittab.

SRC controlled processes must be started and stopped via the SRC interface. If a SRC process dies or is killed the srcmstr daemon will re-spawn that process and log an error to the system error log.

The core process for SRC (srcmstr) is spawned from /etc/initttab. Services that run under SRC control do not leave their process group (ie: have a PPID of 1), but instead, stay children of srcmstr.
List the status of the cdromd service
lssrc -s cdromd
List the status of inetd subservices
lssrc -l -s inetd
List the status of all members of the NFS group
lssrc -g nfs

Start the cdromd service
startsrc -s cdromd
››› There is not a persistent flag for the startsrc command.
For this service to automatically start on the next boot, a change must be made to one of the system initialization files.
In this case, an entry must be made in /etc/initttab.

Stop the cdromd service
stopsrc -s cdromd
Send a refresh request to the syslogd service
refresh -s syslogd
››› This would typically be communicated via a HUP signal.
Not all SRC controlled processes respond to a refresh request and may require a HUP signal.

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