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.
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
