Clustering concepts

Standard clusters

What standard clusters contain

A standard cluster contains two sets of Fibre Channel disk shelves, a local node, and a partner node. The nodes are connected to each other through an IB cluster adapter, which allows a takeover node to serve data to the disks of a failed partner node. Each node continually monitors its partner, mirroring the data for each other's NVRAM. The two nodes in a cluster can be separated from each other by as much as 500 meters, requiring them to be connected with the LC-LC 50/125 cable and connected to their partner disk shelves with SC-SC 50/125 cables.

Advantages of standard clusters

The advantages of having a standard cluster are as follows:

Data continues to be processed if one of the nodes fails and cannot reboot.
Data continues to be processed if an adapter on an node fails.
System maintenance can be performed without interrupting service.

In any of these situations, the takeover node continues to serve data until the problem is corrected.

How Data ONTAP works with standard clusters

In a clustered system, Data ONTAP functions so that each node monitors the functioning of its partner through a heartbeat signal sent between the nodes. Data from the NVRAM of one node is mirrored by its partner and can take over the partner's disks, if the partner should fail. Also, the nodes synchronize each other's time. Any spare disks belonging to one node are not shared by the partner node.

See the Data ONTAP System Administrator's Guide for more information.

Standard cluster setup requirements and restrictions

The following list specifies the requirements and restrictions you must be aware of when setting up a new cluster or converting an existing cluster:

IB cluster adapters and cables must be installed.
Nodes must be attached to the same network and the NICs must be configured correctly.
Cluster software must be licensed and enabled on both nodes.
The same system software must be licensed and enabled on both nodes.