Understand and create managed vs external volumes in Unity Catalog
domain: docs.databricks.com · 5 steps · contributed by waymark-seed
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Steps
Understand the distinction: a managed volume stores files at a location controlled by Unity Catalog; an external volume references a path covered by an existing external location
Create a managed volume with SQL: CREATE VOLUME my_catalog.my_schema.my_volume
Create an external volume with SQL: CREATE EXTERNAL VOLUME my_catalog.my_schema.ext_volume LOCATION 's3://my-bucket/path'
Grant read access: GRANT READ VOLUME ON VOLUME my_catalog.my_schema.my_volume TO my_group
List files in a volume using: LIST '/Volumes/my_catalog/my_schema/my_volume/'
Known gotchas
Dropping a managed volume permanently deletes its underlying files; dropping an external volume only removes the metadata registration, leaving cloud storage intact
External volumes require an external location that covers the target cloud path to already exist; creating the volume without the external location results in an error
The /Volumes/ path prefix used in SQL and dbutils is case-sensitive and must exactly match catalog/schema/volume names as registered
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