Guide for Migration & Configure Opensearch in Magento2.4.4 or greater
In versions 2.4.4 and 2.4.3-p2, all fields labeled Elasticsearch also apply to OpenSearch.
Migrating from elasticsearch to opensearch
When upgrading from Elasticsearch to OpenSearch, settings and indexes are upgraded:
Cluster settings: All dynamic settings that are supported in the new cluster will be migrated, and the ones that were deprecated will be archived.
Indexes: All compatible indexes (that is, all your data) will be readable/writable by the new software version.
Static settings defined in the opensearch.yml or elasticsearch.yml files are not moved automatically during an upgrade. Each version of OpenSearch is bundled with the opensearch-upgrade tool. The tool connects to an Elasticsearch cluster and moves the static settings, and the cluster and the settings are defined in the elasticsearch.yml to opensearch.yml files automatically. If you use ElasticSearch keystore to store secret values, you also can use the opensearch-upgrade tool to automate the migration
things to remember while upgrading
First, back up your data by taking a snapshot of your existing cluster (You can follow the approach outlined in Upgrade to OpenSearch.
Second, verify version compatibility between the existing cluster and the version to which you are migrating. OpenSearch was forked from the last open source version of Elasticsearch, 7.10.2.
Indexes are compatible with current and previous major versions (OpenSearch 1.x or later can read/write indexes from open source Elasticsearch 6.x and 7.x).
Wire compatibility works with all major versions and the minor verison(s) of the latest major version. OpenSearch 1.x or later can join an open source Elasticsearch 6.8.x and 7.x cluster.
Follow this link for upgrade process
Support matrix for open source Elasticsearch to OpenSearch
Open Source Elasticsearch Recommended Upgrade Path
7.0 to 7.10.2 => Restart/Rolling upgrade to OpenSearch 1.x
6.8 => Restart/Rolling upgrade to 7.10.2
6.0 to 6.7 => Restart/Rolling upgrade to 6.8
5.6 => Restart/Rolling upgrade to 6.8
5.0 to 5.5 => Restart/Rolling upgrade to 5.6
Configuration in magento 2.4.4 | 2.4.5 | 2.4.6