Westinghouse Disk Utility, popularly called WDU, is a copy/backup/restore program for IBM's DOS, DOS/VS, and DOS/VSE environments. In 1978, it was reported that WDU, a product of Westinghouse Electric Corporation, was in use at over 3,000 sites. Originally designed for IBM's DOS, Westinghouse continued developing it for subsequent generations, including DOS/VS, DOS/VSE, and VM/CMS. The product offered a wide variety of backup and copy options, , alternating tape drives, and an ability to create archives.