PowerHA SystemMirror software componentsEdit online PowerHA® SystemMirror® software has many components. Cluster secure communication subsystemPowerHA SystemMirror has a common communication infrastructure that increases the security of intersystem communications. Cluster utilities use the Cluster Communications daemon that runs on each node for communication between the nodes.IBM reliable scalable cluster technology availability servicesThe IBM® Reliable Scalable Cluster Technology (RSCT) high availability services provide greater scalability, notify distributed subsystems of software failure, and coordinate recovery and synchronization among all subsystems in the software stack. RSCT reports node and network failures to the PowerHA cluster manager.Cluster manager and SNMP monitoring programsA PowerHA SystemMirror cluster is dynamic and can undergo various transitions in its state over time.Cluster information programThe Cluster Information Program (Clinfo), the clinfo daemon, is an SNMP-based monitor.Highly available NFS serverThe highly available NFS server functionality is included in the PowerHA SystemMirror product subsystem.Shared external disk accessThe PowerHA SystemMirror software supports two methods of shared external disk access: nonconcurrent and concurrent.Concurrent resource managerThe Concurrent resource manager of PowerHA SystemMirror provides concurrent access to shared disks in a highly available cluster, allowing tailored actions to be taken during takeover to suit business needs.Parent topic: PowerHA SystemMirror cluster software