OSTRESS is a Microsoft tool comes with RML utilities package and it uses to stress SQL Server. This is especially useful when you want to troubleshoot SQL Server while SQL Server is under heavy load.
Use below link to download RML Utilities
SQL Server (x64)
After installing RML utilities, you can use RML cmd prompt to execute scripts with OSTRESS.
Type OSTRESS at the RML cmd prompt and you will see all the options as follows;