Why is disk space is not reclaimed by the operating system after records are deleted from a hosted feature service?

In some cases, when a large number of records—including attachments—are deleted from a hosted feature service, the size of the ArcGIS Data Store may still increase, and the disk space is not released back to the operating system (OS).

ArcGIS Data Store uses PostgreSQL as its backend database. When large volumes of data (including attachments) are deleted or updated in PostgreSQL, obsolete rows can remain in the database. As a result, the disk space is not immediately reclaimed by the OS.

Up to ArcGIS Enterprise version 11.3, there was no built-in utility within ArcGIS Data Store to reclaim this disk space. However, starting with version 11.4 (officially documented in 11.5), a new utility called maintaindatastore has been introduced, which has the potential to reclaim unused disk space.

Please refer the following link for more information:

• ArcGIS Datastore Utility Reference