The HMC is a server or stand alone machine that provides a graphical user interface tool to manage several Power Systems. The HMC manages system through hypervisor and operating system. From version 7 it is truly web based and you can configure, installs and manage, partitioned, virtualization most of your Power5 and 6 boxes via HMC. There are many tasks you can do with HMC, such as,

☛ Powering off and on of the partition

☛ Configure and activate resources to the system

☛ Creates and stores LPAR profiles and allocated resources to them.

☛ HMC do the dynamic memory reconfiguration of the partition.

☛ Setup VIO server and VIO client thru HMC and do micro-partition, create storage

☛ pool and processor pool with it

☛ Provide virtual console to the partition

Most of the time we installed dual HMC for redundancy and make sure to achieve more uptime in a wide system.