Characteristics of nodes in an active/active configuration

To configure and manage nodes in an active/active configuration, you should be familiar with the characteristics that all types of active/active configurations have in common.

•	They are connected to each other either through a cluster interconnect consisting of adapters and cable, or, in systems with two controllers in the same chassis, through an internal interconnect. The nodes use the interconnect to do the following tasks:

•	Continually check whether the other node is functioning

•	Mirror log data for each other’s NVRAM

•	Synchronize each other’s time

•	They use two or more disk shelf loops, or third-party storage, in which the following conditions apply:

•	Each node manages its own disks or array LUNs.

•	Each node in takeover mode manages its partner's disks or array LUNs. For third-party storage, the partner node takes over read/write access to the array LUNs owned by the failed node until the failed node becomes available again.

Note: For systems using software-based disk ownership, disk ownership is established by Data ONTAP or the administrator, rather than by which disk shelf the disk is attached to.

•	They own their spare disks, spare array LUNs, or both and do not share them with the other node.

•	They each have mailbox disks or array LUNs on the root volume:

•	Two if it is a FAS system.

•	One if it is a V-Series system.

The mailbox disks or LUNs are used to do the following tasks:

•	Maintain consistency between the pair

•	Continually check whether the other node is running or whether it has performed a takeover

•	Store configuration information that is not specific to any particular node

•	They can reside on the same Windows domain or on different domains.