Planning for a direct-attached configuration

A direct-attached configuration dedicates entire port bandwidth to be used for a specific connection. Planning must account for the volume of expected traffic before you decide how many ports are used in a direct-attached configuration.

The system offers multiple options in deciding how to create a direct-attached configuration. Because of the bandwidth requirements when you are using a direct-attached configuration, it is important to determine the volume of expected traffic in deciding the number of required ports. For example, if a system to system direct-attached link is configured between nodes in an I/O group, then this link carries cache replication traffic. Hence, enough system to system bandwidth needs to be available so that cache replication for host writes can occur without any bandwidth bottleneck.

The following guidelines are provided for direct-attached configurations.

Fibre Channel direct attachment to host systems:
The system allows direct attachment connectivity between its Fibre Channel ports and host ports. Host systems can be connected to 8 Gb or 16 Gb Fibre Channel ports on the system. No special configuration is required for host systems that are using this configuration.
Fibre Channel direct attachment between nodes in a system:
Direct connection of the system Fibre Channel ports without using a Fibre Channel switch is supported. Such direct connections between the system nodes might be useful in small configurations where there is no Fibre Channel switch. It can also be used to connect nodes in the same I/O group to provide a dedicated connection for mirroring the fast write cache data. Ensure that sufficient bandwidth is provisioned between nodes to accommodate all the intra-node traffic.

SAN Volume Controller 2145-DH8 supports 16 Gb Fibre Channel ports. This platform supports Fibre Channel direct attachment on all 16 Gb ports.