Fabric Attached MetroCluster

Definition of a switch fabric

A Fabric Attached MetroCluster contains two fabrics. A switch fabric consists of a switch on the local half of the cluster connected to a switch on the remote half of the cluster. The two switches are connected to each other through long distance ISL cables.

For example, the first fabric in a MetroCluster begins from Switch 1 on the local side and is completed by connecting the ISL to the first switch on the remote side--Switch 3. The second fabric is created using Switch 2 on the local side, connected through a second ISL cable, to the second switch on the remote side--Switch 4.

How switches are divided

The Fibre Channel switches are divided into banks and quadrants. Each switch has two banks and four quadrants, dividing the switch into equal parts. For example, a Brocade 3800 switch has 16 ports, divided into two banks of eight ports per bank.

The banks are further subdivided into two quadrants of four ports each (two for the Brocade 3200). These quadrants are also identified as Pools, which function the same in a Fabric Attached MetroCluster as in a mirrored cluster disk pool. Quadrants 1 and 3 belong to Pool 0, and quadrants 2 and 4 belong to Pool 1. Each switch bank contains a Pool 0 and a Pool 1.

See the Data ONTAP Data Protection Guide for a detailed discussion of disk pools.

The following illustration shows a Brocade 3800 switch, divided into banks, quadrants, and pools.

Advantages of Fabric Attached MetroClusters

The advantages of Fabric Attached MetroClusters are the same as those of both standard and mirrored clusters. See Standard clusters and Mirrored clusters and nonswitched MetroClusters for information about the advantages of each cluster type.

In addition, Fabric Attached MetroClusters have the following advantages:

Expanded distance between halves of the cluster beyond 500 meters.
Disk shelves and nodes are not connected directly to each other, but are connected to a fabric with multiple data routes, ensuring no single point of failure.

How Data ONTAP works with Fabric Attached MetroClusters

Data ONTAP functions the same as it does in a nonswitched MetroCluster. For more information, see How Data ONTAP works with nonswitched MetroClusters.

Setup requirements and restrictions

Cabling a Fabric Attached MetroCluster is the same as for standard or mirrored clusters, with the following exceptions:

Each clustered pair of nodes must use two switches, per cluster side, to communicate with the clients.
Switches must be either Brocade 3200 or 3800 and must be the same type on each side of the MetroCluster.
Each node must have the HBA kit installed and running.
Each node must have the VI-MC cluster adapter installed; slot position is dependent on the type of appliance.
syncmirror_local and cluster_remote must be licensed and enabled on the local and partner nodes.
Mixed switch types can be used, but must be the same type on each side of the cluster.