OpenSearch Dashboards allows you to perform a [force merge]({{site.url}}{{site.baseurl}}/im-plugin/ism/error-prevention/index#force_merge) operation on two or more indexes with **Index Management**.
1. Under **Configure source index**, specify the indexes you want to force merge.
1. Optionally, under **Advanced settings** you can to choose to **Flush indices** or **Only expunge delete** and then specify the **Max number of segments** to merge to as shown in the following image.
To perform a force merge operation on two or more indexes, perform the following steps:
1. Under **Index Management**, choose **Data streams**.
1. Select the data streams you want to force merge.
1. Choose **Actions**, and then choose **Force merge**.
1. Under **Configure source index**, specify the data streams you want to force merge.
1. Optionally, under **Advanced settings** you can to choose to **Flush indices** or **Only expunge delete** and then specify the **Max number of segments** to merge to as shown in the following image.