Overview of ONTAP Cloud HA in multiple Availability Zones

Deploying an ONTAP Cloud HA configuration in multiple Availability Zones (AZs) ensures high availability of your data if a failure occurs with an AZ or an instance that runs an ONTAP Cloud node. You should understand how NAS IP addresses impact data access and storage failover.

NFS and CIFS data access for clients within the VPC

When an ONTAP Cloud HA configuration is spread across multiple Availability Zones, three floating IP addresses are required for NAS data access from within the VPC. The floating IP addresses, which must be outside of the CIDR blocks for all VPCs in the region, can migrate between nodes when failures occur.

These floating IP addresses are not natively accessible to clients that are outside of the VPC.

You should review requirements for floating IP addresses and route tables before you deploy an HA configuration across multiple Availability Zones. You must specify the floating IP addresses when you deploy the configuration.

AWS networking requirements for ONTAP Cloud HA in multiple AZs

NFS and CIFS data access for clients outside the VPC

When deployed in multiple AZs, ONTAP Cloud HA includes a separate set of IP addresses for NAS clients that are outside of the VPC. These IP addresses are static—they cannot migrate between nodes.

iSCSI data access

Cross-VPC data communication is not an issue since iSCSI does not use floating IP addresses.

Storage takeover and giveback for iSCSI

For iSCSI, ONTAP Cloud uses multipath I/O (MPIO) and Asymmetric Logical Unit Access (ALUA) to manage path failover between the active-optimized and non-optimized paths.
Note: For information about which specific host configurations support ALUA, see the NetApp Interoperability Matrix Tool and the Host Utilities Installation and Setup Guide for your host operating system.

Storage takeover and giveback for NAS

When takeover occurs in a NAS configuration using floating IPs, the node's floating IP address that clients use to access data moves to the other node. The following image depicts storage takeover in a NAS configuration using floating IPs. If node 2 goes down, the floating IP address for node 2 moves to node 1.

Conceptual image showing storage takeover in an ONTAP Cloud HA pair: the floating IP addresses from node 1 move to node 2.

NAS data IPs used for external VPC access cannot migrate between nodes if failures occur. If a node goes offline, you must manually remount volumes to clients outside the VPC by using the IP address on the other node.

After the failed node comes back online, remount clients to volumes using the original IP address. This step is needed to avoid transferring unnecessary data between two HA nodes, which can cause significant performance and stability impact.

You can easily identify the correct IP address from Cloud Manager by selecting the volume and clicking Mount Command.