Exhibit 5.1

2550 Hanover Street
Palo Alto, CA 94304-1115

December 27, 2022

Quantum Corporation
224 Airport Parkway, Suite 550
San Jose, CA 95110

Re: Registration Statement on Form S-3

Ladies and Gentlemen:

We are acting as counsel for Quantum Corporation, a Delaware corporation (the “Company”), in connection with the Registration Statement on Form S-3 relating to the registration under the Securities Act of 1933 (the “Act”) of 361,010 shares of common stock, par value $0.01 per share (the “Common Stock”), of the Company, all of which are to be offered and sold by certain stockholders of the Company (the “Shares”). Such Registration Statement, as amended, is herein referred to as the “Registration Statement.”

We have reviewed and are familiar with such documents, corporate proceedings and other matters as we have considered relevant or necessary as a basis for the opinion expressed in this letter. On the basis of the foregoing and the assumptions set forth below, and subject to the other qualifications and limitations set forth herein, we are of the opinion that the Shares have been duly authorized and validly issued and are fully paid and nonassessable.

The opinion set forth in this letter is limited to the General Corporation Law of the State of Delaware, as in effect on the date hereof.

We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the Registration Statement and to the use of our name under the caption “Legal Matters” in the Registration Statement and in the Prospectus forming a part thereof and any supplement thereto. In giving this consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Securities and Exchange Commission promulgated thereunder.

Very truly yours,

/s/ Pillsbury Winthrop Shaw Pittman LLP