POST_START

Creating and Managing External Volumes in Databricks Unity Catalog

I recently needed to set up a new data pipeline for the sales team, and part of that involved organizing raw files stored in an external location. I decided to use Databricks Unity Catalog to create an external volume that would make it easier to manage these files within the Databricks environment.

Setting Up the External Volume

I started by identifying the external location where the raw files were stored. The path was provided by the data engineering team, and it was in the format /raw-files. I knew that creating an external volume would allow me to reference this location more cleanly in my SQL queries and manage access control through Unity Catalog.

I ran the following command to create the external volume:

CREATE EXTERNAL VOLUME training.sales.raw_files LOCATION '/raw-files';

This command created a new external volume named training.sales.raw_files that pointed to the specified location. I verified that the volume was successfully created by checking the metadata in Unity Catalog and confirming that the location was correctly associated with the volume.

Checking Volume Details

Next, I wanted to understand more about the volume I had just created. I used the DESCRIBE VOLUME command to get detailed information about the volume:

DESCRIBE VOLUME training.sales.raw_files;

This command returned details such as the volume name, location, and any associated access controls. I noticed that the volume was now properly registered in Unity Catalog, and I could see the path it was pointing to. This helped me confirm that the volume was set up correctly and ready for use.

Listing All Volumes in the Schema

To ensure there were no other volumes in the training.sales schema that might interfere with my setup, I ran the SHOW VOLUMES IN training.sales command:

SHOW VOLUMES IN training.sales;

This returned a list of all volumes in the specified schema, and I confirmed that training.sales.raw_files was the only one I had created. This step was important to avoid any accidental duplication or conflicts in the volume naming.

Managing the External Volume

Later, after verifying that the volume was being used correctly and that the data was being accessed without issues, I decided to drop the volume as part of a cleanup process. I used the DROP VOLUME command to remove it:

DROP VOLUME training.sales.raw_files;

I made sure to double-check that there were no active queries or data pipelines relying on this volume before proceeding. Once the volume was dropped, I confirmed that it no longer appeared in the list of volumes in the training.sales schema.

Throughout this process, I learned how to effectively create, inspect, and manage external volumes using Databricks Unity Catalog. This approach not only simplifies data access but also enhances security and governance by leveraging Unity Catalog’s metadata management capabilities.