--- layout: "guides" page_title: "Performance Standby Nodes - Guides" sidebar_current: "guides-operations-performance-nodes" description: |- This guide will walk you through a simple Vault Highly Available (HA) cluster implementation. While this is not an exhaustive or prescriptive guide that can be used as a drop-in production example, it covers the basics enough to inform your own production setup. --- # Performance Standby Nodes ~> **Enterprise Only:** Performance Standby Nodes feature is a part of _Vault Enterprise_. In [Vault High Availability](/guides/operations/vault-ha-consul.html) guide, it was explained that only one Vault server will be _active_ in a cluster and handles **all** requests (reads and writes). The rest of the servers become the _standby_ nodes and simply forward requests to the _active_ node. ![HA Architecture](/img/vault-ha-consul-3.png) If you are running **_Vault Enterprise_ 0.11** or later with the Consul storage backend, those standby nodes can handle most read-only requests. For example, performance standbys can handle encryption/decryption of data using [transit](/docs/secrets/transit/index.html) keys, GET requests of key/value secrets and other requests that do not change underlying storage. This can provide considerable improvements in throughput for traffic of this type, resulting in aggregate performance increase linearly correlated to the number of performance standby nodes deployed in a cluster. ## Reference Materials - [Performance Standby Nodes](/docs/enterprise/performance-standby/index.html) - [High Availability Mode](/docs/concepts/ha.html) - [Consul Storage Backend](/docs/configuration/storage/consul.html) - [Vault Reference Architecture](/guides/operations/reference-architecture.html) ## Server Configuration Performance standbys are enabled by default when the Vault Enterprise license includes this feature. If you wish to disable the performance standbys, you can do so by setting the [`disable_performance_standby`](/docs/configuration/index.html#vault-enterprise-parameters) flag to `true`. Since any of the nodes in a cluster can get elected as active, it is recommended to keep this setting consistent across all nodes in the cluster. !> Consider a scenario where a node with performance standby _disabled_ becomes the active node. The performance standby feature is disabled for the whole cluster although it is enabled on other nodes. ## Enterprise Cluster A highly available Vault Enterprise cluster consists of multiple servers, and there will be only one active node. The rest can serve as performance standby nodes handling read-only requests locally. ![Cluster Architecture](/img/vault-perf-standby-1.png) The number of performance standby nodes within a cluster depends on your Vault Enterprise license. Consider the following scenario: - A cluster contains **five** Vault servers - Your Vault Enterprise license allows **two** performance standby nodes ![Cluster Architecture](/img/vault-perf-standby.png) In this scenario, the performance standby nodes running on VM 8 and VM 9 can process read-only requests. However, the _standby_ nodes running on VM 6 and VM 10 simply forward all requests to the active node running on VM 7. > **NOTE:** The selection of performance standby node is determined by the active node. When a node is selected, it gets promoted to become a performance standby. This is a race condition that there is no configuration parameter to specify which nodes to become performance standbys. ## Next steps Read [Production Hardening](/guides/operations/production.html) to learn best practices for a production hardening deployment of Vault.