Linux Clustering With Csm and Gpfs

The System Resource Controller subsystem provides a set of commands and subroutines that make it easier for the system manager and programmer to create and control subsystems in a cluster environment. A subsystem is a program or set of programs that is usually capable of operating independently or with a controlling system. A subsystem is designed as a unit to provide a appointed function.

The SRC was designed to minimize the need for operator intervention. It provides a mechanism to control subsystem processes using a common command line or through the C language programming interface. This mechanism includes the following:

• Consistent user interface for subsystem start, stop, and status inquiries

• Tracing of a subsystem or a group of subsystems

• Support for control of operations on a remote system

• Refreshing of a subsystem (such as after a configuration data change)

The SRC provides a common way to start, stop, and collect status information on processes.

Subsystem components

A subsystem can have one or more of the following properties:

• Is known to the system by a name

• Requires a more complex execution environment than a subroutine or non-privileged program

• Includes application programs and libraries as well as subsystem code

• Controls resources that can be started and stopped by name

• Requires notification if a related process fails in order to perform cleanup or to recover resources

• Requires more operational control than a simple daemon process

• May need to be controlled by a remote operator

• Does not put itself in the background

The lssrc -a command provided by SRC displays a list of active and inactive subsystems. Example A-1 on page 255 show the output of the lssrc -a command on the storage node in our cluster.

Example A-1: lssrc -a command output

[root@storage001 root]# lssrc -a Subsystem Group PID Status cthats cthats 843 active cthags cthags 943 active ctrmc rsct 1011 active ctcas rsct 1018 active IBM.HostRM rsct_rm 1069 active IBM.FSRM rsct_rm 1077 active IBM.CSMAgentRM rsct_rm 1109 active IBM.ERRM rsct_rm 1110 active IBM.AuditRM rsct_rm 1148 active mmfs aixmm 1452 active IBM.SensorRM rsct_rm inoperative IBM.ConfigRM rsct_rm inoperative [root@storage001 root]#

This sample shows subsystems that are installed by CSM Version 1.3.0. These subsystems are described in detail in Chapter 3, "Introducing Cluster Systems Management for Linux" on page 41.

Subsystems can be grouped in a subsystem group in order to allow the administrator control of several subsystems at one time. As shown in Example A-1, subsystems IBM.ERRM, IBM.SensorRM, and IBM.CSMAgentRM are part of the rsct_rm group.

The System Resource Controller has a hierarchical structure. The hierarchy begins with the operating system followed by a subsystem group (such as RSCT), which contains one or more subsystems (such as the GPFS subsystems).