EXHIBIT 5.1

                     [Letterhead of Dewey Ballantine LLP]


                                              February 23, 2000

Equinix, Inc.
901 Marshall Street
Redwood City, CA 94063

Ladies and Gentlemen:

     We have acted as special New York counsel to Equinix,  Inc., a Delaware
corporation (the "Company"), in connection with the Company's offer to exchange
(the "Exchange Offer") up to $200,000,000 aggregate principal amount of its 13%
Senior Notes due 2007 (the "Exchange Notes") which have been registered under
the Securities Act of 1933, as amended (the "Securities Act") for its existing
13% Senior Notes due 2007 (the "Old Notes"), as described in the Prospectus (the
"Prospectus") contained in the Registration Statement on Form S-4 (as amended or
supplemented, the "Registration Statement"), to be filed with the Securities and
Exchange Commission.  The Old Notes were issued, and the Exchange Notes are
proposed to be issued, under an indenture dated as of December 1, 1999 (the
"Indenture"), between the Company and State Street Bank and Trust Company of
California, N.A., as Trustee.

     In arriving at the opinion expressed below, we have examined originals or
copies, certified or otherwise identified to our satisfaction, of such
documents, corporate records, certificates, agreements and other matters as we
have deemed necessary or advisable for the purposes of rendering this opinion.

     In such examination, we have assumed, without independent investigation,
(i) the genuineness of all signatures; (ii) the legal capacity of all
individuals who have executed any of the documents reviewed by us; (iii) the
authenticity of all documents submitted to us as originals; (iv) the conformity
to executed documents of all unexecuted copies submitted to us; (v) the
authenticity of, and the conformity to original documents of, all documents
submitted to us as certified or photocopied copies; (vi) that the Company has
taken all necessary action, corporate and otherwise, to authorize the issuance
and delivery of the Exchange Notes; (vii) that the Company has the power,
corporate and otherwise, to issue and deliver the Exchange Notes; and (viii) the
due execution and delivery of the Exchange Notes.  As to certain factual matters
material to our opinion, we have relied upon oral statements, written
information and certificates of officials and representatives of the Company and
others, and we have not independently verified the accuracy of the statements
contained therein.

     Based on the foregoing, and subject to the assumptions, limitations,
exceptions and qualifications set forth herein, we are of the opinion that the
Exchange Notes, when authenticated, issued and delivered in exchange for the Old
Notes in accordance with the terms of the Indenture and the Exchange Offer, will
constitute valid and binding obligations of the Company, enforceable in
accordance with their terms, except as the enforceability thereof may


be limited by bankruptcy, insolvency, fraudulent conveyance, reorganization or
similar laws affecting creditors' rights generally or by general equitable
principles.

     We are members of the Bar of the State of New York and the foregoing
opinion is limited to the laws of the State of New York as in effect on the date
hereof.

     We hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement and to the reference made to this firm under the caption
"Legal Matters" in the Prospectus.  In giving this consent, we do not thereby
admit that we are included within the category of persons whose consent is
required under Section 7 of the Securities Act, or the rules and regulations of
the Securities and Exchange Commission promulgated thereunder.

     This opinion is rendered solely to you in connection with the above matter.
This opinion may not be relied upon by you for any other purpose or relied upon
by or furnished to any other person without our prior written consent.

                                    Very truly yours,

                                    /s/ Dewey Ballantine LLP
                                    --------------------------------------
                                    DEWEY BALLANTINE LLP


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