# Upgrade a cluster's operating system ```json metadata { "schema_version": 2, "title": "Upgrade a cluster's operating system", "description": "Upgrade a Redis Enterprise Software cluster's operating system to a later major version.", "categories": ["docs","operate","rs"], "tableOfContents": {"sections":[{"id":"prerequisites","title":"Prerequisites"},{"children":[{"id":"extra-node-upgrade","title":"Extra node upgrade method"},{"id":"replace-node-upgrade","title":"Replace node upgrade method"}],"id":"perform-os-rolling-upgrade","title":"Perform OS rolling upgrade"}]} , "codeExamples": [] } ``` To upgrade the operating system (OS) on a Redis Enterprise Software cluster to a later major version, perform a rolling upgrade. Because you upgrade one node at a time, you can upgrade your cluster's OS without downtime. ## Prerequisites Before you upgrade a cluster's operating system: 1. [Upgrade all nodes in the cluster](https://redis.io/docs/latest/operate/rs/installing-upgrading/upgrading/upgrade-cluster) to a Redis Enterprise Software version that supports the OS's current version and upgrade version. To learn which versions of Redis Enterprise Software support specific OS versions, see [Supported platforms](https://redis.io/docs/latest/operate/rs/references/supported-platforms#supported-platforms). 1. If the cluster contains databases that use modules: 1. Update all nodes in the cluster to [Redis Enterprise Software version 7.2.4-52](https://redis.io/docs/latest/operate/rs/release-notes/rs-7-2-4-releases) or later before you upgrade the OS. 1. Check the status of modules using [`rladmin`](https://redis.io/docs/latest/operate/rs/references/cli-utilities/rladmin): ```sh rladmin status modules ``` The output lists the module versions installed on the cluster and the module versions used by existing databases: ```sh CLUSTER MODULES: MODULE VERSION RedisBloom 2.6.3 RediSearch 2 2.8.4 RedisGears 2.0.12 RedisGraph 2.10.12 RedisJSON 2.6.6 RedisTimeSeries 1.10.6 DATABASE MODULES: DB:ID NAME MODULE VERSION ARGS STATUS db:1 db1 RediSearch 2 2.6.9 PARTITIONS AUTO OK, OLD MODULE VERSION db:1 db1 RedisJSON 2.4.7 OK, OLD MODULE VERSION ``` 1. If any databases use custom modules, manually uploaded modules, or modules marked with `OLD MODULE VERSION`, upload module packages for the OS upgrade version to a cluster node. See [Install a module on a cluster](https://redis.io/docs/latest/operate/rs/installing-upgrading/modules/add-module-to-cluster) for instructions. > [!NOTE] > The uploaded module packages have the following requirements: > > - The module is compiled for the OS upgrade version. > > - The module version matches the version currently used by databases. > 1. If the cluster uses custom directories, make sure the OS upgrade version also supports custom directories, and specify the same custom directories during installation for all nodes. See [Customize installation directories](https://redis.io/docs/latest/operate/rs/installing-upgrading/install/customize-install-directories) for details. ## Perform OS rolling upgrade To upgrade the cluster's operating system, use one of the following rolling upgrade methods: - [Extra node method](#extra-node-upgrade) - recommended if you have additional resources available - [Replace node method](#replace-node-upgrade) - recommended if you cannot temporarily allocate additional resources ### Extra node upgrade method {#extra-node-upgrade} 1. Create a node with the OS upgrade version. 1. [Install the cluster's current Redis Enterprise Software version](https://redis.io/docs/latest/operate/rs/installing-upgrading/install/install-on-linux) on the new node using the installation package for the OS upgrade version. 1. [Add the new node](https://redis.io/docs/latest/operate/rs/clusters/add-node) to the cluster. 1. If the [cluster uses DNS](https://redis.io/docs/latest/operate/rs/networking/cluster-dns), add the new node’s IP address to the DNS records. 1. [Remove one node](https://redis.io/docs/latest/operate/rs/clusters/remove-node#remove-a-node) running the earlier OS version from the cluster. 1. Repeat the previous steps until all nodes with the earlier OS version are removed. ### Replace node upgrade method {#replace-node-upgrade} 1. [Remove a node](https://redis.io/docs/latest/operate/rs/clusters/remove-node#remove-a-node) with the earlier OS version from the cluster. 1. Uninstall Redis Enterprise Software from the removed node: ```sh sudo ./rl_uninstall.sh ``` 1. Either upgrade the existing node to the OS upgrade version, or create a new node with the OS upgrade version. 1. [Install the cluster's current Redis Enterprise Software version](https://redis.io/docs/latest/operate/rs/installing-upgrading/install/install-on-linux) on the upgraded node using the installation package for the OS upgrade version. 1. [Add the new node](https://redis.io/docs/latest/operate/rs/clusters/add-node) to the cluster. If you want to reuse the removed node's ID when you add the node to the cluster, run [`rladmin cluster join`](https://redis.io/docs/latest/operate/rs/references/cli-utilities/rladmin/cluster/join) with the `replace_node` flag: ```sh rladmin cluster join nodes username password replace_node ``` 1. If the [cluster uses DNS](https://redis.io/docs/latest/operate/rs/networking/cluster-dns), add the new node’s IP address to the DNS records. 1. Verify node health: 1. Run `rlcheck` on all nodes: ```sh rlcheck ``` The output lists the result of each verification test: ```sh ##### Welcome to Redis Enterprise Cluster settings verification utility #### Running test: verify_bootstrap_status PASS ... Running test: verify_encrypted_gossip PASS Summary: ------- ALL TESTS PASSED. ``` For healthy nodes, the expected output is `ALL TESTS PASSED`. 1. Run [`rladmin status`](https://redis.io/docs/latest/operate/rs/references/cli-utilities/rladmin/status) on the new node: ```sh rladmin status extra all ``` The expected output is the `OK` status for the cluster, nodes, endpoints, and shards: ```sh CLUSTER: OK. Cluster master: 2 () Cluster health: OK, [0, 0.0, 0.0] failures/minute - avg1 0.00, avg15 0.00, avg60 0.00. ... ``` 1. Repeat the previous steps until all nodes with the earlier OS version are replaced.