NEC Express5800 Fault Tolerant Virtual Server Quick Start Guide
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Figure 3: Outcome of adapter and switch failure with AFT.
Switch Fault Tolerant Teams
A Switch Fault Tolerant (SFT) team is similar to an AFT team, except that SFT enables you to connect the team
members to separate switches for increased fault tolerance. An SFT team must contain only two network
adapters, and you must connect each adapter to a different switch that supports the Spanning Tree Algorithm.
As in an AFT team, the primary adapter is active on the network. The secondary adapter becomes active after
adapter failover, which usually occurs because the primary adapter fails or if its link to the switch fails.
In a SFT team, each adapter connects to a different switch; this configuration can continue operation if a switch
fails.
Figure 4 shows the SFT configuration and the outcome of adapter and switch failure.
Figure 4: Outcome of adapter and switch failure with SFT.
Adaptive Load Balancing Teams
In an Adaptive Load Balancing (ALB) team, both the primary and secondary adapters transmit data to provide
an increase in performance. However, only the primary adapter receives data. To prevent packet-order
problems, one adapter in an ALB team transmits all packets to a particular destination. In addition, only the
primary adapter transmits broadcast packets and non-Internet Protocol (IP) packets. You must connect all
adapters in an ALB team to the same switch or to two or more hubs that connect to the same switch.
In addition, an ALB team provides fault tolerance for the network connection, but because both adapters
connect to the same switch, like an AFT team, if the switch fails, network connectivity is lost.
Configuring Power Inputs
Irrespective of the amount of resources in your system and fault tolerant configurations, if your system loses
power, not only will its resources be unavailable, but you may also lose or corrupt data. When the server is
running multiple virtual machines, sudden loss of power to the server will have a critical impact on your network
infrastructure.
