Exhibit 8.1


                       [LETTERHEAD OF ERNST & YOUNG LLP]

                                June 10, 1999

Quantum Corporation
500 McCarthy Boulevard
Milpitas, Ca 95035


Ladies and Gentlemen:

        We have acted as the tax advisor to Quantum Corporation ("Quantum") in
connection with the proposed adoption of an amended and restated certificate of
incorporation which would result in the exchange of its existing class of
outstanding common stock for two new classes of common stock of Quantum.

        We have examined the Registration Statement on Form S-4 (the
"Registration Statement"), including the preliminary Proxy Statement and
Prospectus dated June 10, 1999 that forms a part thereof, relating to the
above-described transaction. In addition, we have examined such other documents,
obtained such certifications of officers, and have made such other and further
investigations, as we have deemed relevant and necessary as a basis for the
opinion hereinafter set forth. In such examination, we have assumed the
authenticity of all documents submitted to us as originals, the conformity to
originals documents of all documents submitted to us a draft or as certified,
conformed, photostatic or facsimile copies, and the authenticity of the
originals of such latter documents. We have also assumed that all information,
statements and descriptions in the Registration Statement, officers certificates
and other relevant documents are true, correct and complete in all material
aspects and any statement subject to a knowledge qualification is true without
such qualification.

        Based upon the foregoing, we hereby confirm that, subject to the
qualifications and limitations stated herein and in the Registration Statement,
our opinion set forth in the Registration Statement under "Proposal 1--The
Tracking Stock Proposal" with respect to "United States Federal Income Tax
Considerations" under the captions "Tax Implications of the Tracking Stock
Proposed to Stockholders" and "Tax Implications of a Conversion of DSSG Stock or
HDDG Stock", insofar as they purport to constitute a summary of matters of
United States federal tax law and regulations or legal conclusions with respect
thereto, constitute an accurate description of the matters described therein in
all material respects.



        Our opinion is based upon the Internal Revenue Code of 1986, as amended,
the Treasury regulations promulgated thereunder and other relevant authorities
and law, all as in effect on the date hereof. No opinion is expressed except as
specifically set forth in the above-referred captions. This opinion merely
represents our best judgment based on existing authorities, none of which
directly addresses the Federal income tax consequences of the issuance of
multiple classes of stock of a single corporation which are intended to
separately track the economic performance of different businesses of the issuer.
The Internal Revenue Service is not precluded from successfully asserting a
position contrary to that set forth in the above-referenced captions. Finally,
future interpretations of, or changes in, the law may cause the tax treatment of
the transactions referred to herein to be materially different from that
described above, including, but not limited to the proposed change described
under "Proposal 1--The Tracking Stock Proposal" with respect to "United States
Federal Income Tax Considerations" under the caption "Clinton Administration
Proposal". nevertheless, we undertake no responsibility to notify you of any
subsequent development.

        We hereby consent to the filing of this opinion with the Securities and
Exchange Commission as an exhibit to the Registration Statement and to the
reference to our firm under the appropriate headings in the prospectus that
forms a part of the Registration Statement.



                                                Very truly yours,

                                                /s/ Ernst & Young LLP


Palo Alto, California