Configuring Redundant HMCs

This document discusses configuration issues when installing redundant HMCs.

In situations requiring high availability, administrators may want to configure redundant HMCs. A redundant HMC
manages a system that is already managed by another HMC. When there are two HMCs managing one system,
those HMCs are peers and can be used to simultaneously manage the same system(s).

Requirements
o Each system can be managed by a maximum of two HMCs.
o Redundant HMCs that are managing the same managed system must be at the same version of HMC Code.
o On servers with dual FSPs, each HMC must have an active network connection to both FSPs.

Features
The following considerations must be taken into account when designing a redundant HMC network:

o	Private Network versus Open Network The following models require that the HMC be connected to the server using a private network with the HMC configured as a DHCP server on the private network; static IP addresses are not supported: POWER5 590/595, POWER6 9119-FHA, POWER7 9119-FHB. A private network is also recommended for 9406-570s that have the optional dual FSP feature. An open network with static addresses can be used to manage all other models.
o	Maintenance The HMC is used for service operations and concurrent maintenance. At least one HMC, or a workstation with remote access to a HMC, should be located close to the managed system to allow for maintenance operations.
o	Service Events The HMC Service Functions provide the ability to report and manage service events. In a redundant HMC configuration, both HMCs must have one interface on the same network for this function to work properly. Each HMC attempts to detect a redundant HMC and, when detected, negotiates a primary/secondary role for handling service events. Only the primary performs problem analysis and repair on service events. In the event the primary HMC shuts down or fails, the secondary takes over.
o	5250 Console The 5250 Console shared session function does not work between redundant HMCs. Only one HMC can have an active 5250 console at any one time.

Sample Configurations
Figure 1 is taken from the eServer Information Center. It shows a dual private network configuration. Each HMC is
connected to one port of each FSP of each server being managed using an isolated private network. Note: This is the recommended configuration.



Figure 2 shows a mixed private/open network configuration.

This figure shows two HMCs. Each HMC manages local systems on a private network with the HMC configured as
a DHCP server. Each HMC also manages the remote system(s) over the open network using a static address. This
may be desired when one HMC is in a remote location and a private network cannot be configured to the system
being managed.




Dual Private Network: Adding a Redundant HMC to an Existing System
These instructions are for the configuration shown in Figure 1 (dual private networks). It describes how to add a
second HMC using a new private network connection.

Note: Do not connect an Ethernet cable to the second HMC port of the server being managed until directed to do so.

o Record the IP addresses used by the existing HMC. On the existing HMC, open a restricted shell (right click the desktop, click terminals, then rshterm). Type the following command:

lshmc -n.

The output is similar to the following:

hostname=cs6hmc,domain=rchland.ibm.com,"ipaddr=192.168.0.1,9.5.32.12",
"networkmask=255.255.0.0,255.255.255.0",gateway=9.5.32.1,"nameserver=9.10.244.100,9.10.244.200",
"domainsuffix=rchland.ibm.com,ibm.com",
ipaddrlpar=9.5.32.12,networkmasklpar=255.255.255.0,clients=192.168.255.254

Note the ipaddr field and networkmask fields. These are the existing IP addresses in use. In the example above:
eth0: 192.168.0.1/255.255.0.0
eth1: 9.5.32.12/255.255.255.0

o Configure the new HMC as a DHCP server.

Version 6 and earlier: On the HMC being added, click HMC Management, HMC Configuration, Customize Network Settings. On the Customize Network Settings tab, click LAN Adapters, click eth0, and click the Details button. Configure eth0 for a Private network. Check Enable DHCP server. Click the Address range dropdown box, and select a dhcp address range that is different than the other HMC. The address range chosen must also be different than the subnet used on any other interface such as eth1 or eth2. Click OK.

In the example above, the next available address range (172.16.0.3-172.16.255.254) can be used because this does not conflict with the first HMC eth0 address or the open network.

o Configure the new HMC open interface. The new redundant HMC must have an interface on the same network as the original HMC (and the partitions) for error reporting to work correctly.

Version 6 and earlier: In the Customize Network Settings panel, click eth1, and then click the Details button. Configure eth1 as an open network. Type the desired IP address and subnet mask, click OK, and click OK again. Configure the Name Services information using the Name Services tab. Type a default gateway for eth1 on the Routing tab. Click OK. The user is notified that the changes will go into effect after the next reboot. Click OK.

o Reboot the HMC, and log back in. Verify the settings.

o Cable the HMC

Plug the Ethernet cable into the HMC eth0 port and the FSP HMC2 port. If a hub is used first connect the HMC eth0 port to the hub, connect the FSP HMC2 port to the hub. The order is important because the FSP starts requesting an IP address as soon as the link goes active. In approximately three minutes, the managed system should appear on the HMC under "Server Management" in a state of failed authentication.

o Type the HMC Access password. Right-click on the managed system, and select enter/update managed system password. Type the HMC access password.

Private/Static Network: Adding a Redundant HMC to an Existing System
These instructions are for the configuration shown in Figure 2 where the HMC being added connects over an
open network. This assumes the existing HMC is connected using a private network and that the new HMC being
added will connect over an open (static IP) network.

o Obtain static IP addresses

Have the network administrator assign static IP addresses on the open network for each FSP on each server to be managed by the remote HMC. This information should include the following:
-- IP address
-- Subnet
-- Default gateway
-- Host name (recommended)
-- DNS server (recommended)

Note: For dual FSP servers, ensure that an IP address is obtained for both FSPs.

o Configure the HMC open network interface (if needed)
The new HMC must have an interface configured with a route (connection) to the desired systems.

By convention, most HMCs have two or more Ethernet ports. eth0 is configured as a DHCP server on a private network for locally attached servers. eth1 is configured on the open network (a static address or DHCP client).

To configure an interface for use on the open network, expand HMC Management, HMC configuration, and click Customize Network Settings. In the Customize Network Settings panel, click eth1, and click the Details button. Configure eth1 as an open network. Type the desired IP address and subnet mask, click OK, and click OK again. Configure the Name Services information using the Name Services tab. Enter a default gateway for eth1 on the Routing tab. Click OK. The user is notified that the changes will go into effect after the next reboot. Click OK. Reboot the HMC, and log back in. Verify the settings.

o Configure the FSP(s) port for a static address

This procedure can be done while the system is running for all POWER5 servers at firmware 230 or higher and all POWER6 and later servers.

Advanced System Manager (ASM) must be used to change the FSP network configuration. ASM can be accessed using a PC running a supported browser or through an HMC that is already connected to the managed system.

To use the HMC, select Service Applications, Service Focal Point, and then Service Utilities. On the Service Utilities dialog, click the System Processor. Then, click the menu option Selected, and Launch ASM Menu. The Web browser is launched to the ASM sign-on screen.

If the HMC has never successfully connected to the FSP, access ASM using the procedure described in the eServer Information Center Topic Accessing the ASMI using a Web browser at: http://publib.boulder.ibm.com/infocenter/eserver/v1r3s/topic/iphby/browser.htm.

Do the following:

a.	Sign on ASM using the admin user account.
b.	Expand Network Services and Network Configuration.
c.	Record the current settings for both interfaces. The interface used by the existing HMC will have an ip address with the same subnet as the existing HMCs private interface. The unused interface to be configure should be at its default value.
d.	Select the option Configure this interface on the unused interface. Change the Type of IP address to Static. Type the static IP address and Subnet mask. Type the default gateway. Type a host name and domain name, if desired. Select the option to continue and then save.

e. On servers with dual FSP, repeat this step for the second FSP.

o Cable the FSP to the network
Cable the unused FSP port (HMC1 or HMC2) to the network.
The IP address should reply to pings on the network.

o Add the system to the HMC
On the HMC, Expand Server and Partition, and click Server management. Click the menu Server management then Add Managed Systems. Type the FSP information in the IP address/host name field. Type the HMC access password. Click Next, and then click Finish.

The system is shown under system management within a few minutes.

On servers with dual FSP, repeat this step for the second FSP's IP address.