Multus public and cluster networks

Using both Multus public and cluster networks simultaneously provides dedicated networks for different types of storage traffic.

The following diagram shows the cluster network architecture for a Fusion Data Foundation deployment using both Multus public network and Multus cluster network:

When both public and cluster networks are used simultaneously, all three benefits of Multus are achieved. In this case, each storage network performs a specific role in the Fusion Data Foundation cluster. The public network handles only the I/O traffic from applications and the cluster network handles storage replication and recovery traffic.

The cluster network handles data replication traffic on a regular basis. Assuming Fusion Data Foundation's default 3x replication, the cluster network handles 2x the application I/O traffic for each data write to bring the total number of storage data copies up to 3x. During a storage node or zone failure event, the cluster network also handles recovering data in the cluster.

In this architecture, the size of the cluster network is recommended to be 2-3x larger than the public network. Larger sizing keeps the failover times short, but it also results in a large amount of bandwidth being wasted during normal cluster operations. Overall storage bandwidth during a storage failure event might be limited by either the public or cluster network depending on the size of either network.

This architecture is more complicated than the recommended public-only architecture and has many more factors that could affect user SLOs. Hence, as an alternative, Fusion Data Foundation suggests bonding all storage network interfaces together to create a single, larger public network instead.