Exhibit 99.1

Execution Version

VOTING AGREEMENT

THIS VOTING AGREEMENT (this “Agreement”) is made and entered into as of June 23, 2013, by and between Western Digital Corporation, a Delaware corporation (“Parent”), and the undersigned shareholder (“Holder”) of sTec, Inc., a California corporation (the “Company”).

RECITALS

Pursuant to an Agreement and Plan of Merger, dated as of the date hereof (the “Merger Agreement”), by and among Parent, Lodi Ventures, Inc., a California corporation and wholly-owned subsidiary of Parent (“Merger Sub”), and the Company, Merger Sub is merging with and into the Company (the “Merger”) and the Company, as the surviving corporation of the Merger, will thereby become a wholly-owned subsidiary of Parent. Concurrently with the execution and delivery of the Merger Agreement and as a condition and inducement to Parent and Merger Sub to enter into the Merger Agreement, Parent has required that Holder enter into this Agreement. Holder is the beneficial owner (within the meaning of Rule 13d-3 of the Exchange Act) of that number of shares of the outstanding Common Stock, par value $0.001 per share, of the Company as is indicated beneath Holder’s signature on the last page of this Agreement (the “Shares”); provided, that, Shares subsequently transferred as permitted in Section 1(b) below shall from and after such transfer cease to be considered “Shares” under this Agreement. Capitalized terms used herein but not defined shall have the meanings ascribed to them in the Merger Agreement.

AGREEMENT

The parties agree as follows:

1. Agreement to Retain Shares.

(a) Transfer. During the period beginning on the date hereof and ending on the Expiration Date (as defined in Section 6 below), (1) except as contemplated by the Merger Agreement, and except as provided in Section 1(b) below, Holder agrees not to, directly or indirectly, sell, transfer, exchange or otherwise dispose of (including by merger, consolidation or otherwise by operation of law) the Shares, and (2) Holder agrees not to, directly or indirectly, grant any proxies or powers of attorney, deposit any of the Shares into a voting trust or enter into a voting agreement with respect to any of the Shares, or enter into any agreement or arrangement providing for any of the actions described in this clause (2).

(b) Permitted Transfers. The parties acknowledge and agree that nothing set forth in this Agreement shall be deemed to prohibit or otherwise restrict the ability of Holder, (i) if Holder is an individual, to transfer or otherwise dispose of any Shares to any family member of Holder or trust for the benefit of Holder or any family member of Holder (“family member” shall include any spouse, lineal ancestor or descendant, brother or sister, whether by blood or in law, of Holder), (ii) if Holder is an entity, to transfer or otherwise dispose of any Shares to any shareholder, affiliated fund, member, beneficiary or partner of Holder, (iii) to transfer or otherwise dispose of any Shares to a charitable organization qualified under Section 501(c)(3) of the Internal Revenue Code of 1986, as amended, (iv) in connection with or

for the purpose of personal tax-planning, or (v) to transfer or otherwise dispose of any Shares if required by any order of any Governmental Entity, Law or operation of Law; provided, that, the assignee or transferee under clauses (i) (except in the case of a transfer by will or under the laws of intestacy), (ii), (iii) and (iv) agrees to be bound by the terms of this Agreement and executes and delivers to the parties hereto a written consent memorializing such agreement.

(c) New Shares. Holder agrees that any shares of outstanding Company Common Stock that Holder purchases or with respect to which Holder otherwise acquires record or beneficial ownership after the date of this Agreement and prior to the Expiration Date shall be subject to the terms and conditions of this Agreement to the same extent as if they constituted Shares on the date of this Agreement.

2. Agreement to Vote Shares.

(a) Until immediately after the Expiration Date, at every meeting of the shareholders of the Company called with respect to any of the following, and at every adjournment thereof, and on every action or approval by written consent of the shareholders of the Company with respect to any of the following, Holder shall appear at such meeting (in person or by proxy) and shall vote or consent the Shares (i) in favor of the approval of the Merger Agreement and the Merger and (ii) against any Acquisition Proposal (the “Covered Proposals”). This Agreement is intended to bind Holder as a shareholder of the Company only with respect to the Covered Proposals. Except as expressly set forth in clauses (i) and (ii) of this Section 2(a), Holder shall not be restricted from voting in favor of, against or abstaining with respect to any other matter presented to the shareholders of the Company. Until the Expiration Date, Holder covenants and agrees not to enter into any agreement or understanding with any person with respect to voting of its Shares on any Covered Proposal which conflicts with the terms of this Agreement. Notwithstanding anything to the contrary herein, Holder shall not be required to vote or consent the Shares in favor of any proposal to amend the Merger Agreement or take any other action that would result in the amendment, modification or waiver of any provision therein, in each case, which would decrease the amount of or change the form of the Merger Consideration.

(b) Holder further agrees that, until the Expiration Date, Holder will not, and will not permit any entity under Holder’s control to, (A) solicit proxies or become a “participant” in a “solicitation” (as such terms are defined in Regulation 14A under the Exchange Act) in opposition to any proposal or action in favor of the approval of the Merger Agreement and the Merger, (B) initiate a shareholders’ vote with respect to an Acquisition Proposal or (C) become a member of a “group” (as such term is used in Section 13(d) of the Exchange Act) with respect to any voting securities of the Company with respect to an Acquisition Proposal.

(c) Subject to the provisions set forth in Section 5 hereof, and as security for Holder’s obligations under Section 2(a), Holder hereby irrevocably constitutes and appoints Parent and its designees as his attorney-in-fact and proxy in accordance with the California Corporations Code, with full power of substitution and resubstitution, to cause the Shares to be present at the Company Shareholders Meeting, to vote his Shares at the Company Shareholders Meeting, however called, and, if applicable, to execute consents in respect of his Shares with respect to the Covered Proposals. For the avoidance of doubt, the proxy granted by Holder under

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this Section 2(c) shall only pertain to matters concerning the Covered Proposals and Holder does not grant to Parent a proxy with respect to the matters contemplated by the third and fifth sentences of Section 2(a). SUBJECT TO THE PROVISIONS SET FORTH IN SECTION 6 HEREOF, THIS PROXY AND POWER OF ATTORNEY IS IRREVOCABLE AND COUPLED WITH AN INTEREST. Upon the execution of this Agreement, Holder hereby revokes any and all prior proxies or powers of attorney given by Holder with respect to voting of the Shares on the Covered Proposals and agrees not to grant any subsequent proxies or powers of attorney with respect to the voting of the Shares on any Covered Proposal until after the Expiration Date. Holder understands and acknowledges that Parent is entering into the Merger Agreement in reliance upon Holder’s execution and delivery of this Agreement and Holder’s granting of the proxy contained in this Section 2(c). Holder hereby affirms that the proxy granted in this Section 2(c) is given in connection with the execution of the Merger Agreement, and that such proxy is given to secure the performance of the duties of Holder under this Agreement.

3. Representations, Warranties and Covenants of Holder. Holder hereby represents, warrants and covenants to Parent that Holder (i) is the beneficial owner of the Shares (within the meaning of Rule 13d-3 under the Exchange Act), which, at the date of this Agreement and at all times up until the Expiration Date, will be free and clear of any liens, claims, options, charges or other encumbrances (other than those created by this Agreement) and (ii) as of the date hereof does not own of record or beneficially any shares of outstanding capital stock of the Company other than the Shares (excluding shares as to which Holder currently disclaims beneficial ownership in accordance with applicable law). Holder has the legal capacity, power and authority to enter into and perform all of Holder’s obligations under this Agreement (including under the proxy granted in Section 2(c) above). This Agreement (including the proxy granted in Section 2(c) above) has been duly and validly executed and delivered by Holder and constitutes a valid and binding agreement of Holder, enforceable against Holder in accordance with its terms, subject to (a) laws of general application relating to bankruptcy, insolvency and the relief of debtors and (b) rules of law governing specific performance, injunctive relief and other equitable remedies.

4. No Solicitation. Holder hereby represents and warrants that he or she has read Section 6.4 of the Merger Agreement and agrees to be bound by the provisions of such section.

5. Appraisal Rights. Holder waives and agrees not to exercise any rights (including, without limitation, under Section 1300 the California Corporations Code) to demand appraisal of any of the Shares which may arise with respect to the Merger.

6. Termination. This Agreement and the proxy delivered in connection herewith shall terminate and shall have no further force and effect as of the earlier to occur of (i) the date of termination of the Merger Agreement in accordance with the terms and provisions thereof, and (ii) the Effective Time (the earlier of such dates, the “Expiration Date”).

7. Fiduciary Duties. Notwithstanding anything in this Agreement to the contrary: (i) Holder makes no agreement or understanding herein in any capacity other than in Holder’s capacity as a beneficial owner of the Shares, (ii) nothing in this Agreement shall be

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construed to limit or affect Holder’s rights and obligations as a director, officer, or other fiduciary of the Company, and (iii) Holder shall have no liability to Parent, Merger Sub or any of their Affiliates under this Agreement as a result of any action or inaction by Holder acting in his capacity as a director, officer, or other fiduciary of the Company.

8. No Ownership Interest. Nothing contained in this Agreement shall be deemed to vest in Parent or any of its Affiliates any direct or indirect ownership or incidence of ownership of or with respect to any Shares. All rights, ownership and economic benefit of or relating to the Shares shall remain vested in and belong to Holder, and Parent shall have no authority to manage, direct, superintend, restrict, regulate, govern or administer any of the policies or operations by the Company or exercise any power or authority with respect to Holder in the voting of any of Shares, except as specifically provided herein.

9. Miscellaneous.

(a) Notices. All notices and other communications hereunder shall be in writing and shall be deemed duly given (a) on the date of delivery if delivered personally, or if by facsimile or email, upon written confirmation of receipt by facsimile, email or otherwise (provided that any notice received by facsimile transmission, email or otherwise at the addressee’s location on any day that is not a Business Day or on any Business Day after 5:00 pm (local time) shall be deemed to have been received at 9:00 am (local time) on the next Business Day), (b) on the first Business Day following the date of dispatch if delivered utilizing a next-day service by a recognized international next-day courier, or (c) on the earlier of confirmed receipt or the fifth Business Day following the date of mailing if delivered by registered or certified mail, return receipt postage requested, postage prepaid. All notices hereunder shall be delivered to the addresses on the signature pages set forth below, or pursuant to such other instructions as may be designated in writing by the party to receive such notice.

(b) Entire Agreement. This Agreement constitutes the entire agreement, and supersedes all prior written agreements, arrangements, communications and understandings and all prior and contemporaneous oral agreements, arrangements, communications and understandings between the parties with respect to the subject matter hereof.

(c) Governing Law. This Agreement and all disputes or controversies arising out of or relating to this Agreement or the transactions contemplated hereby shall be governed by, and construed in accordance with, the internal laws of the State of Delaware, without regard to the laws of any other jurisdiction that might be applied because of the conflicts of laws principles of the State of Delaware, provided, that the laws of the State of California shall govern with respect to California corporate law issues.

(d) Submission to Jurisdiction. Each of the parties irrevocably agrees that any action arising out of or relating to this Agreement or the transactions contemplated hereby brought by any party or its Affiliates against any other party of its Affiliates shall be brought and determined exclusively in a federal or state court located within Orange County, California. Each of the parties hereby irrevocably submits to the jurisdiction of the aforesaid courts for itself and with respect to its property, generally and unconditionally, with regard to any such action arising out of or relating to this Agreement and the transactions contemplated hereby. Each of

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the parties hereto agrees not to commence any action arising out of or relating to this Agreement or the transactions contemplated hereby except in the courts described above in Orange County, California, other than actions in any court of competent jurisdiction to enforce any judgment, decree or award rendered by any such court in Orange County, California as described herein. Each of the parties hereto further agrees that notice as provided herein shall constitute sufficient service of process and the parties further waive any argument that such service is insufficient. Each of the parties hereby irrevocably and unconditionally waives, and agrees not to assert, by way of motion or as a defense, counterclaim or otherwise, in any action arising out of or relating to this Agreement or the transactions contemplated hereby, (a) any claim that is not personally subject to the jurisdiction of the courts in Orange County, California as described herein for any reason, (b) that it or its property is exempt or immune from jurisdiction of any such court or from any legal process commenced in such courts (whether through service of notice, attachment prior to judgment, attachment in aid of execution of judgment, execution of judgment or otherwise), and (c) that (i) the action in any such court is brought in an inconvenient forum, (ii) the venue of such action is improper or (iii) this Agreement, or the subject matter hereof, may not be enforced in or by such courts.

(e) Amendment or Supplement. This Agreement may not be amended, modified or supplemented in any manner, whether by course of conduct or otherwise, except by an instrument in writing, signed by each of the parties.

(f) Assignment; Successors. Neither this Agreement nor any of the rights, interests or obligations under this Agreement may be assigned or delegated, in whole or in part, by operation of law or otherwise, by either party without the prior written consent of the other party, and any such assignment without such prior written consent shall be null and void. Subject to the preceding sentence, this Agreement will be binding upon, inure to the benefit of, and be enforceable by, the parties and their respective permitted successors and assigns.

(g) Enforcement. The parties hereto agree that that irreparable damage would occur and the parties hereto would not have an adequate remedy at law in the event that any of the provisions of this Agreement were not performed in accordance with their specific terms or were otherwise breached. Accordingly, the parties hereto agree that each party shall be entitled to seek specific performance of the terms hereof, including an injunction or injunctions to prevent breaches of this Agreement and to enforce specifically the terms and provisions of this Agreement. Each of the parties hereto hereby further waives (a) any defense in any action for specific performance that a remedy at law would be adequate and (b) any requirement under any law to post security as a prerequisite to obtaining equitable relief.

(h) Severability. Whenever possible, each provision or portion of any provision of this Agreement shall be interpreted in any manner as to be effective and valid under applicable law, but if any provision or portion of any provision of this Agreement is held to be invalid, illegal or unenforceable in any respect under any applicable law or rule in any jurisdiction, such invalidity, illegality or unenforceability shall not affect any other provision or portion of any provisions in such jurisdiction, and this Agreement shall be reformed, construed and enforced in such jurisdiction as if such invalid, illegal or unenforceable provision or portion of any provision had never been contained herein.

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(i) Waiver of Jury Trial. EACH PARTY HERETO ACKNOWLEDGES AND AGREES THAT ANY CONTROVERSY WHICH MAY ARISE OUT OF OR RELATE TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY IS LIKELY TO INVOLVE COMPLICATED AND DIFFICULT ISSUES, AND THEREFORE EACH PARTY HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES ANY RIGHT SUCH PARTY MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY ACTION DIRECTLY OR INDIRECTLY ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED BY THIS AGREEMENT. EACH PARTY HERETO CERTIFIES AND ACKNOWLEDGES THAT (a) NO AGENT, ATTORNEY OR OTHER REPRESENTATIVE OF ANY OTHER PARTY HERETO HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF ANY ACTION, SEEK TO ENFORCE THE FOREGOING WAIVER, (b) EACH PARTY HERETO UNDERSTANDS AND HAS CONSIDERED THE IMPLICATIONS OF THIS WAIVER, (c) EACH PARTY HERETO MAKES THIS WAIVER VOLUNTARILY AND (d) EACH PARTY HERETO HAS BEEN INDUCED TO ENTER INTO THIS AGREEMENT, BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS IN THIS SECTION 9(i).

(j) Counterparts. This Agreement may be executed in two or more counterparts, all of which shall be considered one and the same instrument and shall become effective when one or more counterparts have been signed by each of the parties and delivered by Parent, on one hand, and Holder, on the other hand, to the other. Signatures to this Agreement transmitted by facsimile transmission, by electronic mail in PDF form, or by any other electronic means designed to preserve the original graphic and pictorial appearance of a document, will be deemed to have the same effect as physical delivery of the paper document bearing the original signatures.

[SIGNATURE PAGE FOLLOWS]

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IN WITNESS WHEREOF, the parties have caused this Voting Agreement to be duly executed on the date first above written.

Signature Page to Voting Agreement

Signature Page to Voting Agreement

SPOUSAL CONSENT

The undersigned represents that the undersigned is the spouse of:

and that the undersigned is familiar with the terms of the Voting Agreement (the “Agreement”), entered into as of June 23, 2013, by and between Western Digital Corporation, a Delaware corporation, and the undersigned’s spouse. The undersigned hereby agrees that the interest of the undersigned’s spouse in all property which is the subject of such Agreement shall be irrevocably bound by the terms of such Agreement and by any amendment, modification, waiver or termination signed by the undersigned’s spouse. The undersigned further agrees that the undersigned’s community property interest in all property which is the subject of such Agreement shall be irrevocably bound by the terms of such Agreement, and that such Agreement shall be binding on the executors, administrators, heirs and assigns of the undersigned. The undersigned further authorizes the undersigned’s spouse to amend, modify or terminate such Agreement, or waive any rights thereunder, and that each such amendment, modification, waiver or termination signed by the undersigned’s spouse shall be binding on the community property interest of undersigned in all property which is the subject of such Agreement and on the executors, administrators, heirs and assigns of the undersigned, each as fully as if the undersigned had signed such amendment, modification, waiver or termination.

Spousal Consent to Voting Agreement