QUANTUM CORPORATION EXHIBIT 21 SUBSIDIARIES OF REGISTRANT 1. Quantum International Inc., a California corporation 2. Quantum International DISC Inc., a California corporation 3. Quantum Foreign Sales Corporation, a Barbados corporation 4. Quantum GmbH, a German corporation 5. Quantum Peripheral Products Ltd., a United Kingdom corporation 6. Quantum France SARL, a French corporation 7. Quantum Asia Pacific Pte. Ltd., a Singapore corporation 8. Quantum Peripherals Japan Corporation, a Japanese corporation 9. Quantum Data Storage B.V., a Netherlands corporation 10. Quantum Peripheral Products (Ireland) Ltd., an Ireland corporation 11. Quantum Peripherals (Europe) S.A., a Swiss corporation 12. Quantum Singapore Pte. Ltd., a Singapore corporation 13. Quantum Korea Corporation, a Korean corporation 14. Quantum Hong Kong Ltd., a Hong Kong corporation 15. Quantum Peripherals (Malaysia) Sdn. Bhd., a Malaysian corporation 16. Quantum Storage (Malaysia) Sdn. Bhd., a Malaysian corporation 17. Quantum Peripherals Realty Corporation, a Delaware corporation 18. ATL Products, Inc., a Delaware Corporation