5.5.2 LAN configuration

(1) Preventing a single point of failure

HA Monitor does not directly handle LAN failures, such as failures in HUB and LAN adapters. To handle these failures, the following methods can be employed to create a configuration that prevents a LAN from becoming a single point of failure:

• HUB redundancy

• LAN adapter redundancy using a kernel extension package in Linux, such as a bonding package

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(2) IP addresses to be assigned to the servers

You specify alias IP addresses for servers. You can specify multiple alias IP addresses for the same server. Note the following about specifying alias IP addresses for servers:

• The source address of a program that is subject to the hot standby operation must be an alias IP address.

• A host name that has an alias IP address must not be used as a local host name that is set by using the hostname(1) command. If the host is switched over during the hot standby operation, a program that obtains IP addresses from host names can no longer function on the source host.

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(3) IP address configuration

HA Monitor switches LANs for each alias IP address assigned to a server. Therefore, if a hot-standby configuration consists of multiple servers, you must configure network addresses in such a manner that each server uses a different alias IP address. If you use a resource server, you can share a single alias IP address among multiple servers.

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(4) VMware ESXi-based virtualization configuration

If you use a VMware ESXi-based virtualization configuration, a LAN adapter and a host bus adapter (HBA) can be shared among or used exclusively by the virtual machines.

To ensure reliability, we recommend that you use a redundant configuration as described below by using functions provided in VMware ESXi.

• Provide two LAN adapters each for redundancy when configuring the reset path or the VMware ESXi-connection reset path.

• Provide two host bus adapters for redundancy.

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