NetApp HCI Manual page 17

compute resources. Starting with NetApp HCI 1.8, you can have a storage cluster with
two nodes. A storage cluster appears on the network as a single logical group and can
then be accessed as block storage.
The storage layer in NetApp HCI is provided by NetApp Element software and the management layer is
provided by the NetApp Element Plug-in for vCenter Server. A storage node is a server containing a collection
of drives that communicate with each other through the Bond10G network interface. Each storage node is
connected to two networks, storage and management, each with two independent links for redundancy and
performance. Each node requires an IP address on each network. You can create a cluster with new storage
nodes, or add storage nodes to an existing cluster to increase storage capacity and performance.
Authoritative storage clusters
The authoritative storage cluster is the storage cluster that NetApp Hybrid Cloud Control uses to authenticate
users.
If your management node only has one storage cluster, then it is the authoritative cluster. If your management
node has two or more storage clusters, one of those clusters is assigned as the authoritative cluster and only
users from that cluster can log into NetApp Hybrid Cloud Control. To find out which cluster is the authoritative
GET /mnode/about token_url
cluster, you can use the API. In the response, the IP address in the field is
the management virtual IP address (MVIP) of the authoritative storage cluster. If you attempt to log into NetApp
Hybrid Cloud Control as a user that is not on the authoritative cluster, the login attempt will fail.
Many NetApp Hybrid Cloud Control features are designed to work with multiple storage clusters, but
authentication and authorization have limitations. The limitation around authentication and authorization is that
the user from the authoritative cluster can execute actions on other clusters tied to NetApp Hybrid Cloud
Control even if they are not a user on the other storage clusters. Before proceeding with managing multiple
storage clusters, you should ensure that users defined on the authoritative clusters are defined on all other
storage clusters with the same permissions.
You can manage users with NetApp Hybrid Cloud Control.
Before proceeding with managing multiple storage clusters, you should ensure that users defined on the
authoritative clusters are defined on all other storage clusters with the same permissions. You can manage
users from the Element software user interface (Element web UI).
See Create and manage storage cluster assets for more information on working with management node
storage cluster assets.
Stranded capacity
If a newly added node accounts for more than 50 percent of the total cluster capacity, some of the capacity of
this node is made unusable ("stranded"), so that it complies with the capacity rule. This remains the case until
more storage capacity is added. If a very large node is added that also disobeys the capacity rule, the
previously stranded node will no longer be stranded, while the newly added node becomes stranded. Capacity
should always be added in pairs to avoid this from happening. When a node becomes stranded, an appropriate
cluster fault is thrown.
Two-node storage clusters
Starting with NetApp HCI 1.8, you can set up a storage cluster with two storage nodes.
• You can use certain types of nodes to form the two-node storage cluster. See NetApp HCI 1.8 Release
Notes.