Enabled trace flag 3042 to skip the pre-allocation space and I ran a 300 GB database backup with compression. However, enabling the trace flag did not help, instead SQL Server pre-allocated the backup file size. The pre-allocation space is causing to generate false disk space alert. Is there another method/configuration that can be used to skip the pre-allocation space? Thanks!
BACKUP DATABASE DatabaseName TO DISK = N'D:\Backup\DatabaseName.bak'
WITH COPY_ONLY, COMPRESSION, STATS = 10