When provisioning a VDB, the Delphix Engine modifies the "access control lists" (ACLs) of database and log files to help prevent unintentional data loss through file deletion. Files could be deleted, for example, if there is an attempt to DROP a VDB directly through SQL Server management studio or other native SQL Server tools.
The Delphix Engine updates each database and log file ACL to include a deny-delete "access control entry" (ACE) for the user account running the SQL Server instance.
You can still drop VDBs directly through SQL Server tools. However, a warning message will be displayed, and the files will remain on the volume that the Delphix Engine exports. This file deletion prevention also applies to attempts to remove files from a database using the ALTER DATABASE .. REMOVE FILE command.
If a VDB is inadvertently dropped, you can reattach the database using SQL Server tools.
If you attempt to delete a database or log file and then try to add a file of the same name, this may fail because the original file was prevented from being deleted by the deny-delete ACE.
If you intend to delete the files from the volume that the Delphix Engine provides, you can change the ACLs on the files using the icacls command:
icacls <file> /remove <SQL Server instance account>:deny(D)
Accounts other than the SQL Server instance account will not be prevented from deleting the VDB database and log files.