Cluster Management; Hardware Management Console - IBM Power Systems 775 Manual

The disk enclosure includes the following features:
A disk enclosure is one quarter, one half, three quarters, or fully populated with HDDs and
eight SSDs. The disk enclosure always is populated with eight SSDs.
Disk enclosure contains two GPFS recovery groups (RGs). The carriers that hold the
disks of the RGs are distributed throughout all of the STOR domains in the drawer.
A GPFS recovery group consists of four SSDs and one to four declustered arrays (DAs) of
47 disks each.
Each DA contains distributed spare space that is two disks in size.
Every DA in a GPFS system must be the same size.
The granularity of capacity and throughput is an entire DA.
RGs in the GPFS system do not need to be the same size.

1.7 Cluster management

The cluster management hardware that supports the Cluster is placed in 42 U, 19-inch racks.
The cluster management requires Hardware Management Consoles (HMCs), redundant
Executive Management Servers (EMS), and the associated Ethernet network switches.

1.7.1 Hardware Management Console

The HMC runs on a single server and is used to help manage the Power 775 servers. The
traditional HMC functions for configuring and controlling the servers are done via xCAT. For
more information, see 1.9.3, "Extreme Cluster Administration Toolkit" on page 72.
The HMC is often used for the following tasks:
During installation
For reporting hardware serviceable events, especially through Electronic Service Agent™
(ESA), which is also commonly known as call-home
By service personal to perform guided service actions
An HMC is required for every 36 CECs (1152 LPARs) and all Power 775 system have
redundant HMCs. For every group of 10 HMCs, a spare HMC is in place. For example, if a
cluster requires four HMCs, five HMCs are present. If a cluster requires 16 HMCs, the cluster
has two HMCs to serve as spares.
1.7.2 Executive Management Server
The EMS is a standard 4U POWER7 entry-level server responsible for cluster management
activities. EMSs often are redundant; however, a simplex configuration is supported in smaller
Power 775 deployments.
At the cluster level, a pair of EMSs provide the following maximum management support:
512 frames
512 supernodes
2560 disk enclosures
Chapter 1. Understanding the IBM Power Systems 775 Cluster
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