The Deploying an HA NFS Cluster with DRBD and DRBD Reactor on RHEL 9 or AlmaLinux 9 tech guide gives instructions for setting up and configuring a high-availability (HA) NFS three-node cluster, by using DRBD® and DRBD Reactor.
DRBD Reactor is a cluster resource manager developed by LINBIT® that can be simpler to configure and implement than a Pacemaker and Corosync solution. You can even use Open Cluster Framework (OCF) resource agents in your configurations, as the deployment in this guide uses.
After following the instructions in the guide, you will have an HA NFS share on a LAN. Even if one of the cluster nodes fails, DRBD Reactor will fail over the NFS share to another node. A client can continue to access the NFS share during a failover event, even in the middle of accessing a file on the share.