IBM HACMP - High Availability Cluster Multi-processing



High availability clustering on IBM p-series servers running AIX or Linux is achieved using HACMP

HACMP stands for High Availability Cluster Multi-processing

IBM's Reliable Scalable Cluster Technology (RSCT) which includes daemons responsible for monitoring the state of the cluster, is used heavily by HACMP


Main HACMP and RSCT daemons

Cluster Manager Daemon - clstrmgrES

The main HACMP daemon that maintains a global view of the cluster and runs event scripts in response to changes or user requests. It maintains updated information about the location and status of all resource groups.
From HACMP V5.3 the clstrmgr daemon is started via init process and should always be running.

Cluster Lock Manger daemon - cllockd

cllockd provides advisory locking services.
Not supported from HACMP V5.2.

Cluster Communication Daemon - clcomdES

Provides secure communication between cluster nodes.
The clcomd daemon is started automatically at boot time by the init process. Starting with Version 5.2, clcomdES must be running before any cluster services can be started.

Cluster Information Program - clinfoES

The clinfoES daemon provides status information about the cluster to cluster nodes and clients and calls the /usr/es/sbin/cluster/etc/clinfo.rc script in response to a cluster event. The clinfo daemon is optional on cluster nodes and clients.

Cluster SMUX Peer daemon - clsmuxpd

clsmuxpd maintains status information about cluster objects and publishes this information to the MIB. It is a client of the cluster manager and works with the Simple Network Management Protocol (snmpd) daemon. The clsmuxpd daemon must run on all nodes.
No longer exists from HACMP V5.3.

Cluster Topology Services Subsystem - topsvcsd

The RSCT Toplogy Services subsystem monitors the status of network interfaces and use the daemons hatsd and hats_nim.

Cluster Group Services Subsystem - hagsd

This RSCT subsystem provides reliable communication and protocols required for cluster operation.

Cluster Globalized Server daemon - grpglsmd

This RSCT daemon operates as a Group Services client; its function is to make switch adapter membership global across all cluster nodes. All cluster nodes must run the grpglsmd daemon.

Resource Monitoring and Control Subsystem

This RSCT subsystem acts as a resource monitor for the event management subsystem and provides information about the operating system characteristics and utilization. The RMC subsystem must be running on each node in the cluster. By default the rmcd daemon is setup to start from inittab when it is installed. The rc.cluster script ensures the RMC subsystem is running.


HACMP log files

Log files