The Why and How of Load Sharing for VIOS Shared Ethernet Adapters
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Here are some helpful resources on setting up Shared Ethernet Adapters.
If you've worked with dual Virtual I/O Servers (VIOS), you've most likely got experience with Shared Ethernet Adapters (SEAs). You can set them up in failover mode or using the more recent load sharing. With failover, the Ethernet adapters on the backup SEA (for example, on VIO server 2) sit idle until there is a planned or unplanned failure on VIOS1's SEA. In other words, SEAs in failover mode is a binary configuration: if SEA on VIOS1 is up, then your physical Ethernet adapters in the SEA on VIOS2 are sitting idle. Clearly, with expensive 10 Gb physical Ethernet adapters, you don't want them parked in the garage until your main set of wheels breaks down.
With load sharing, you can set some VLANs to use the SEA on VIOS1, and other VLANs to use VIOS2, and still have both SEAs ready to take over should its cousin on the other VIOS fail.
Now if you're having trouble getting your head around all of this, there's a very helpful, hands-on document from our friends at chmod666.org called Optimizing network Part 1: VIO Server load sharing. It not only explains what load sharing is, and how it differs from failover mode. It also provides some great screen shots along with a step-by-step guide on setting up load sharing. There are many very helpful commands you can run to look at what a running configuration looks like.
If you're trying to get your head around SEAs and Load Sharing (sometimes called Load Balancing), have a read of Optimizing network Part 1: VIO Server load sharing.
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