The details in the link below should help...
Creating a highly available (HA) Tableau Server installation
A high availability Tableau Server installation is a special type of distributed installation, designed to accommodate failure in key server components without loss of complete server functionality. To create an HA installation, follow the same steps you take to create a distributed deployment but include additional steps to make the deployment highly available. These additional steps include adding at least two additional nodes (for a minimum of three nodes in the cluster), adding a second instance of the repository, and second instances of the data engine/file store, adding additional gateway processes, and deploying a Coordination Service ensemble. You can also add a load balancer to distribute requests among the gateways.
At a high level, these are the steps you follow to create a highly available installation of Tableau Server:
- Begin by installing Tableau Server on your initial node.For details, see Install and Configure Tableau Server.
- Generate a node configuration (bootstrap) file on the initial node.For details, see Install and Configure Additional Nodes.
- Install Tableau Server on at least two additional nodes using the node bootstrap file.For more information, see Install and Configure Additional Nodes.
- Configure each additional node with the processes you want to run on it. These must include a second copy of the Tableau Server repository, and a second copy of the data engine and file store, as well as additional instances of the gateway.For more information, see Install and Configure Additional Nodes.
- Deploy a Coordination Service ensemble.For more information, see Deploy a Coordination Service Ensemble .
- (Optional) Configure a load balancer.For more information, see Add a Load Balancer.
For details on how to create a three-node HA installation, see Example: Install and Configure a Three-Node HA Cluster.
I would like to know in terms of hardware how much CPU, memory and disk I will need. Based on what factors do I need to consider to calculate it? Is it number of concurrent users accessing it?
Additional detail in the link below (for a single node install, the hardware recommendations are stated. For a multi-node install your best bet may be to contact your Tableau Account Manager)
Hope this helps