Exhibit 10.3

MAXTOR CORPORATION,

SEAGATE TECHNOLOGY,

SEAGATE TECHNOLOGY (US) HOLDINGS, INC.

and

U.S. BANK NATIONAL ASSOCIATION,

TRUSTEE

SECOND SUPPLEMENTAL INDENTURE

Dated as of June 1, 2009

Supplementing the Indenture dated as of March 1, 1987,

as amended by the First Supplemental Indenture dated as of January 11, 1996

The SECOND SUPPLEMENTAL INDENTURE, dated as of June 1, 2009 (this “ Second Supplemental Indenture ”), by and among MAXTOR CORPORATION, a Delaware corporation (the “ Company ”), SEAGATE TECHNOLOGY, an exempted company incorporated with limited liability under the laws of the Cayman Islands (“ Parent ”), SEAGATE TECHNOLOGY (US) HOLDINGS, INC., a Delaware corporation (“ Holdings ”), and U.S. BANK NATIONAL ASSOCIATION, as Trustee (the “ Trustee ”).

RECITALS

WHEREAS, the Company has heretofore executed and delivered to the Trustee an indenture, dated as of March 1, 1987 (the “ Indenture ”), as supplemented and amended by a Supplemental Indenture, dated as of January 11, 1996 (the “ First Supplemental Indenture ”), providing for the creation and issuance by the Company of 5.75% Convertible Subordinated Debentures due 2012 (the “ Securities ”).

WHEREAS, the Company is a wholly owned direct subsidiary of Holdings, and Holdings is a wholly owned indirect subsidiary of Parent;

WHEREAS, in accordance with Section 801(1), the Company previously provided for conversion rights in accordance with Section 1301 of the Indenture in the First Supplemental Indenture;

WHEREAS, in accordance with Section 1306, the Company previously provided notice to Holders on April 28, 2006 regarding the merger of MD Corporation, a Delaware corporation, with and into the Company, whereby the Company continued as the surviving and continuing corporation and became a wholly owned subsidiary of Parent;

WHEREAS, the Company and Holdings have entered into an Assignment and Assumption Agreement, dated as of June 1, 2009 (the “ Assignment and Assumption Agreement ”), by and between the Company and Holdings, pursuant to which: (i) the Company will assign all of the Company’s assets to Holdings (the “ Assignment ”); and (ii) Holdings will assume the Company’s obligations under the Securities and the Indenture (the “ Assumption ”);

WHEREAS, the Company, Parent and Holdings have entered into an Agreement of Merger, dated as of June 1, 2009 (the “ Merger Agreement ”), by and among the Company, Parent and Holdings, pursuant to which, immediately following the Assignment and the Assumption: (i) the Company will merge with and into Holdings (the “ Merger ”, and together with the Assignment and the Assumption, the “ Transactions ”); (ii) Holdings will continue as the surviving and continuing corporation and succeed to and assume all the rights and obligations of the Company in accordance with the Delaware General Corporation Law; and (iii) Parent will unconditionally guarantee the obligations of Holdings under the Securities and the Indenture, as supplemented and amended by the First Supplemental Indenture;

WHEREAS, pursuant to Section 801 of the Indenture, the Company, Parent, Holdings and Trustee have agreed in connection with the Transactions to execute this Second Supplemental Indenture to provide for (i) the assumption by Holdings of the due and punctual payment of the principal of and interest on all the Securities and the performance of every covenant of the Indenture, as supplemented and amended by the First Supplemental Indenture, on the part of the Company to be performed or observed and (ii) the full and unconditional guaranty by Parent of Holdings’ obligations to the Holders of the Securities;

WHEREAS, Section 901(1) of the Indenture provides that the parties hereto may execute this Second Supplemental Indenture without the consent of the Holders of the Securities;

WHEREAS, in accordance with Section 1306 of the Indenture, the Company issued notice to Holders regarding the Transactions at least 20 days prior to the date hereof;

WHEREAS, in accordance with Section 903 of the Indenture, the Trustee is authorized to execute and deliver this Second Supplemental Indenture;

WHEREAS, in accordance with Section 801(1) of the Indenture, Holdings is a corporation organized and existing under the laws of the state of Delaware;

WHEREAS, in accordance with Section 801(2) of the Indenture, immediately after giving effect to the Transactions, no event of default under the Indenture and no event which, after notice or lapse of time or both, would become an event of default under the Indenture, has occurred; and

WHEREAS, in accordance with Sections 102 and 801(3) of the Indenture, as supplemented and amended by the First Supplemental Indenture, the Trustee has received an Officers’ Certificate and an Opinion of Counsel of the Company relating to the Transactions and this Second Supplemental Indenture.

NOW, THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, the Company, Parent, Holdings and the Trustee, acting for itself