Wednesday, February 13, 2013

NetApp Cluster, HA Pair Difference and Confusion

Personally I always get confused over these terms and with the Cluster Mode of NetApp it becomes even more confusing. This post is just to clarify the basics on the terminology used.

What is a NetApp HA Pair

 An HA pair consists of 2 identical controllers; each controller actively provides data services and has redundant cabled paths to the other controller’s disk storage. If either controller is down for any planned or unplanned reason, its HA partner can take over its storage and maintain access to the data. When the downed system rejoins the cluster, the partner will give back the storage resources.

Olden day meaning of Cluster: The term cluster has been used historically to refer to an HA pair running Data ONTAP 7G or 7-Mode. But not anymore.

What is a NetApp Cluster then:

The term cluster now refers only to a configuration of one or more HA pairs running clustered Data ONTAP.

7- Mode, Cluster Mode and Clustered Data ONTAP:

There are 2 variants of NetApp ONTAP operating systems.

1) 7-mode
2) Cluster Mode or C-Mode or the new name Clustered Data ONTAP.