High Availability with Redundant HMC Configuration

Introduction:

Ensuring high availability in IBM Power environments depends heavily on the reliability of the Hardware Management Console (HMC).

Although production LPARs continue running if an HMC fails, administrative control, monitoring, firmware management, and service operations become unavailable. A redundant HMC configuration eliminates this risk by deploying two HMCs managing the same Power Systems.

A properly configured redundant HMC environment provides:

• Continuous system management access
• Automatic Primary / Secondary role negotiation
• Redundant service event management
• Zero administrative downtime during HMC failure

Redundant HMC Overview

In a redundant configuration:

• Two HMCs manage the same Power System
• Both connect to the system’s FSP (Flexible Service Processor)
• One HMC becomes Primary
• The other becomes Secondary
• Roles are automatically negotiated
• If Primary fails, Secondary assumes control

Both HMCs:

• See the same managed systems
• Receive hardware events
• Maintain synchronized awareness of the system

Design Options for Redundant HMC

There are two supported high-availability designs:

Option A — Dual Private Network (Recommended)

Architecture Concept

• Each HMC connects to a separate FSP port
• Each uses its own isolated private network
• HMC acts as DHCP server for FSP
• Networks do not overlap

Option B — Private + Static (Open) Network

Architecture Concept

• Primary HMC uses private DHCP network
• Secondary HMC connects remotely via open/static IP network
• FSP configured with static IP
• Used for remote HMC
• Used when isolated private network not possible

Requirements

Before configuring redundancy:

• Two installed HMCs (HMC-A and HMC-B)
• Both running compatible HMC versions
• Available FSP HMC1 and HMC2 ports
• Network cables and switch ports
• Admin credentials for FSP / ASMI
• IP addressing plan prepared

Option A — Dual Private Network (Recommended)

Assumptions

• Existing HMC = HMC-A
• New HMC = HMC-B
• HMC-A private interface = eth0
• HMC-A open/service interface = eth1
• New DHCP range for HMC-B = 172.16.0.3 – 172.16.255.254
• FSP HMC2 port available

Step-by-Step Configuration:

Step 1 — Record HMC-A Network Configuration

On HMC-A:

lshmc -n

Document:

eth0 IP / subnet

eth1 IP / subnet

Gateway

DNS settings

Step 2 — Configure HMC-B Private Interface (eth0)

On HMC-B:

Navigate:

HMC Management → HMC Configuration → Customize Network Settings

Select:

eth0 → Details

Set:

Network Type = Private

Enable DHCP Server

DHCP Range = 172.16.0.3–172.16.255.254

Ensure no IP conflict with HMC-A.

Step 3 — Configure HMC-B Open Interface (eth1)

Select:

eth1 → Details

Set:

Network Type = Open

Static IP (same subnet as HMC-A eth1)

Gateway

DNS

Reboot HMC-B to apply changes.

Step 4 — Cable Connections

Connect:

HMC-B eth0 → Server FSP HMC2 port

Important:

Power up HMC network before enabling FSP connection

Avoid cross-network overlap

Step 5 — Accept Managed System on HMC-B

Wait for system discovery.

Navigate:

Server Management
Right-click detected system:
Enter/Update Managed System Password
Enter FSP credentials.

Step 6 — Verify Redundancy

Run:

lshmc -n

Confirm:

Both HMCs show valid IPs

Managed system appears in both GUIs

One HMC = Primary

One HMC = Secondary

Validation Checklist (Option A)

• ping <fsp-ip> works from both HMCs
• Managed system visible on both HMCs
• Roles show Primary / Secondary
• Shutdown HMC-A → HMC-B becomes Primary
• No event management interruption

Option B — Private + Static (Open Network Remote HMC)

Used when HMC-B is remote and connects over open network.

Assumptions

• HMC-A uses private DHCP (eth0)
• HMC-B connects remotely via static IP (eth1)
• FSP must be configured with static IP

Step-by-Step Configuration

Step 1 — Obtain Static IP Information

From Network Team:

FSP static IP

Subnet mask

Gateway

DNS

If dual FSP system, obtain both IPs.

Step 2 — Configure HMC-B Open Interface

Navigate:

HMC Management → HMC Configuration → Customize Network Settings

Select:

eth1 → Details

Set:

Network Type = Open

Static IP

Subnet

Gateway

DNS

Reboot HMC-B.

Step 3 — Configure FSP Static IP (via ASMI)

Access ASMI:

Service Applications → Service Focal Point → Service Utilities → Launch ASM

Navigate:

Network Services → Network Configuration

Configure unused FSP interface as:

• Static IP
• Subnet mask
• Gateway

Save and exit.

Step 4 — Connect FSP to Open Network

Connect FSP port to production/open network.

Verify:

ping <fsp-static-ip>

Step 5 — Add Managed System to HMC-B

Navigate:

Server and Partition → Server Management → Add Managed Systems

Enter:

FSP IP

Credentials

System should appear.

Validation Checklist (Option B)

• FSP static IP responds to ping
• Managed systems visible on HMC-B
• Dual FSP connections visible (if applicable)
• Events synchronized between HMCs
• Primary / Secondary roles visible

Role Management Behavior

• Primary HMC handles service events
• Secondary HMC remains synchronized
• Automatic failover occurs if Primary becomes unavailable
• No impact to running LPAR workloads