Exhibit 10.1

KeyBank Real Estate Capital

Institutional Real Estate Group

127 Public Square

Cleveland, OH  44114

April 14, 2015

Mrs. Kimberly Sheehy

Chief Financial Officer

CyrusOne

1649 W. Frankford Road

Carrollton, TX 75007

Re:          Senior Unsecured Bridge Loan (the “Facility”) for CyrusOne LP (the “Borrower”).

Mrs. Sheehy:

KeyBank National Association (“KeyBank”) is pleased to inform the Borrower of KeyBank’s agreement to be the sole and exclusive administrative agent (in such capacity, the “Agent”) for the Facility (as defined below) to the Borrower as described in this Commitment Letter herein dated April 14, 2015 (this “Commitment Letter”), the Term Sheet dated April 14, 2015 attached hereto (the “Term Sheet”), the Mandate Letter April 14, 2015 attached hereto (the “Mandate Letter”) and the Fee Letter dated April 14, 2015 (the “Fee Letter”); this Commitment Letter, the Term Sheet, the Mandate Letter and the Fee Letter are hereinafter collectively referred to as the Mandate Documents) in connection with the Acquisition as described below.  In connection with the forgoing, subject only to the conditions set forth in this Commitment Letter and the section entitled “Conditions Precedent to Funding” contained in the Term Sheet attached hereto, KeyBank is further pleased to advise you of its commitment to lend to the Borrower $300,000,000 of a $300,000,000 bridge loan facility (the “Facility”).  KeyBanc Capital Markets (“KeyBanc”) will act as the Lead Arranger for the Facility (KeyBank in such capacity, the “Lead Arranger”).

The Borrower has informed us that the Borrower intends to acquire (the “Acquisition”) 100% of the outstanding equity interest of the Target.  The Acquisition of the Target may be effected pursuant to a merger of the Target with a wholly-owned subsidiary of the Borrower, with the Target being the surviving entity (although alternative acquisitions structures are being considered by the Borrower).  In addition to financing the Acquisition, the proceeds of the Facility will be used to pay costs and expenses incurred in connection with the closing of the Acquisition, the Facility and related transactions.

Capitalized terms not defined herein shall have the meaning given such terms in the Mandate Letter or the Term Sheet, as applicable.

Prior to and after the execution of Loan Documents (as defined below) for the Facility, KeyBank reserves the right to syndicate all or a portion of the Facility to one or more financial institutions and institutional lenders that will become parties to the Loan Documents, as Lenders, subject to the terms of the Loan Documents.  Upon the acceptance by KeyBank or KeyBanc of a commitment for the Facility from a lender approved by you (such approval not to be unreasonably withheld or delayed) and the funding of such approved lender’s commitment, KeyBank shall be released from a corresponding amount of its Commitment for the Facility.

Until the closing date of the Facility, KeyBank’s commitment hereunder is also subject to the following conditions precedent:  (a) satisfaction of each of the conditions set forth in the section entitled “Conditions Precedent to Funding” set forth in the Term Sheet; (b) the negotiation, execution, and delivery of customary definitive

documentation with respect to the Facility based on documentation relating to the credit facility evidenced by the Existing Credit Agreement and consistent with the terms and conditions of this Commitment Letter, with such changes as are described in the Term Sheet and otherwise satisfactory to Borrower, the Agent, and their respective counsel (the “Loan Documents”); and (c) the payment of fees and expenses and other amounts due and payable on or prior to the Closing Date as provided in the Mandate Documents (which fees and expenses shall have been invoiced at least two business days prior to being due and payable and which amounts may be offset against proceeds of the Facility).

Notwithstanding anything in this Commitment Letter or the other Mandate Documents or any other letter agreement or other undertaking concerning the financing of the Acquisition to the contrary, (i) the only representations and warranties which shall be a condition to availability and funding of the Facility on the Closing Date shall be (A) such of the representations made by the Target or its affiliates in the Acquisition Agreement that are material to the interests of the Lenders, but only to the extent that you have the right to terminate your obligations under the Acquisition Agreement as a result of a breach of such representations in the Acquisition Agreement (the “Acquisition Agreement Representations”), (B) the Specified Representations (as defined below) and (C) such other representations and warranties which would otherwise need to be true and correct in all material respects pursuant to the Existing Credit Agreement in order to satisfy the requirements for a funding thereunder and (ii) the terms of the Loan Documents shall be in a form such that they do not impair availability of the Facility on the Closing Date if the conditions expressly set forth in clauses (b) and (c) in the paragraph immediately above and the conditions contained in the section entitled “Conditions Precedent to Funding” in the Term Sheet are satisfied.  For purposes hereof, “Specified Representations” means the representations and warranties made by the Borrower and each Guarantor in the Loan Documents as to corporate status, corporate power and authority to enter into the Loan Documents; the due authorization, execution, delivery and enforceability of the Loan Documents; the Loan Documents not conflicting with charter documents of the Company and each Guarantor or law; solvency as of the Closing Date of the Borrower and the Guarantors on a consolidated basis; Federal Reserve margin regulations; use of proceeds of the Facility not violating anti-money laundering, anti-terrorism and anti-bribery laws, the Patriot Act or OFAC; and the Investment Company Act.  This paragraph, and the provisions herein, shall be referred to as the “Certain Funds Provisions”.

Neither this offer nor the undertaking and commitment contained herein may be disclosed to or relied upon by any other person or entity other than your members, accountants, attorneys and other advisors, without the prior written consent of the Agent and KeyBanc or as required by law, court order or the rules of the New York Stock Exchange, except that following your acceptance hereof you may make public disclosure hereof in the form pre-approved by KeyBank and KeyBanc.  Notwithstanding the foregoing, the Borrower may disclose this Commitment Letter and the other Mandate Documents (other than the Fee Letter) to the Target and its officers, directors, employees, affiliates, independent auditors, legal counsel and other advisors (collectively, the “Target Parties”) on a confidential basis in connection with the Acquisition and the other transactions contemplated thereby; provided, however, that no Target Party shall thereby be deemed to be a third party beneficiary of this Mandate Letter or any other Mandate Document or have any right to rely or be justified in relying upon the commitment or any of the other undertakings or agreements of any Credit Party contained herein or therein.

By your signature below, you agree that the indemnity included in the Mandate Letter (subject to the exceptions set forth therein) shall include matters arising from this Commitment Letter as well as those arising from the Mandate Letter.

Neither KeyBank nor KeyBanc shall be required to pay any brokerage fees or commissions arising from the issuance of this Commitment Letter or the Facility and you and Borrower agree to defend, indemnify and hold KeyBank and KeyBanc harmless from and against any and all cost, claim, liability, damage or expense (including but not limited to reasonable attorneys’ fees) in connection therewith; provided, however, that KeyBank and KeyBanc will be solely responsible for the fees or commissions of any brokers, finders or originators with whom KeyBank or KeyBanc shall have entered into a written agreement pursuant to which KeyBank or KeyBanc shall have agreed to pay a fee or

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commission in connection with the issuance of this Commitment Letter or the Facility.

The identity of the Borrower, the Guarantors (as defined in the Term Sheet) and the members, owners, partners, officers and managers of such entities is of material importance to KeyBank and KeyBanc and this commitment shall not be assigned by Borrower without the prior written consent of KeyBank and KeyBanc.  Neither KeyBank nor KeyBanc shall have any obligation hereunder to any third party.

No statements, agreements or representations, oral or written, which may have been made prior to the date hereof either by KeyBank or KeyBanc, or by any employee, agent, attorney or broker acting on such person’s behalf, with respect to this commitment or the Facility, shall be of any force or effect, except to the extent stated in this Commitment Letter or in the other Mandate Documents, and all prior agreements and representations in respect of this commitment and the Facility are merged herein so that this Commitment Letter (including the other Mandate Documents) shall contain the entire agreement with respect to the Facility.  This Commitment Letter and its interpretation and enforceability shall be governed and construed under the laws of the State of New York.  The provisions of this Commitment Letter may not be changed except by written agreement signed by you, KeyBank and KeyBanc, except that KeyBank reserves the right to waive, in whole or in part, any of the terms or conditions herein which are for KeyBank’s benefit (including but not limited to the right to extend any outside date for the closing of the Facility), but no such waiver shall be effective unless in writing signed by KeyBank.

Subject to the following sentence, you acknowledge that KeyBank and KeyBanc may share any information delivered or made available by you to it with potential lenders and participants in and assignees of the Facility.  KeyBank and KeyBanc will treat as confidential all confidential information provided to us by or on behalf of you hereunder or under any other Mandate Document, provided that nothing herein shall prevent us from disclosing any such information (i) as may be required by law, or compelled in a judicial or administrative proceeding or requested by a governmental authority, (ii) to the extent that such information becomes publicly available other than by reason of disclosure by us in violation of this paragraph, (iii) to our officers, directors, employees, affiliates, independent auditors, legal counsel and other advisors and service providers on a confidential basis, and (iv) to actual or potential lenders or participants in the Facility who agree to be bound by the terms of this paragraph or substantially similar confidentiality provisions, provided that our confidentiality obligations under this sentence shall terminate on the Closing Date.

In no event shall KeyBank be liable to you or Borrower for any damages caused or alleged to be caused by the failure of any lender other than KeyBank to fund its proportionate share of the Facility.  Furthermore, in no event shall KeyBank be liable to you or Borrower for punitive damages, exemplary damages or consequential damages, including, without limitation lost profits, as a result of or in connection with KeyBank or any other lender failing or refusing to fund the Facility, or for a breach of any nature by KeyBank or any other lender of its obligations under or in connection with this Commitment Letter or the Facility prior to or simultaneous with the funding of the Facility, and you and Borrower waive all claims for punitive damages, exemplary damages and consequential damages in connection with KeyBank or any other lender failing or refusing to fund the Facility or any portion thereof, and in connection with any and all breaches on the part of KeyBank or any or all lenders that may occur prior to or simultaneous with the funding of the Facility.  You, Borrower, KeyBank and KeyBanc hereby irrevocably waives any and all right to trial by jury in any action, proceeding or counterclaim arising out of or relating to this Commitment Letter, the other Mandate Documents, the transactions contemplated hereby and thereby or the actions of KeyBank or KeyBanc in the negotiation, performance or enforcement hereof.

This commitment will expire on the earlier to occur of (a) 5:00 p.m. (Eastern Time) on July 31, 2015, unless prior to such date the Loan Documents have been negotiated, executed and delivered by all parties and the Borrower has satisfied all conditions precedent herein, in the other Mandate Documents and to be specified in the Loan Documents to the funding of the Facility and (b) the date of any termination of the merger agreement relating to the Acquisition.  Notwithstanding anything contained herein or in any other Mandate Document to the contrary, (a) the commitment

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will be reduced by the amount of net cash proceeds raised and received by the Borrower, after the date hereof, under the accordion to the Existing Credit Agreement and all net cash proceeds received by REIT, Borrower and/or any of their respective subsidiaries from any subsequent debt or equity offering that occurs after the execution and delivery of the Mandate Documents by the Borrower, but prior to the Closing Date, provided that the foregoing shall not apply to any revolving credit indebtedness incurred under the Existing Credit Agreement (other than increases in the total commitment under the Existing Credit Agreement) or, in the ordinary course of business, capital leases or purchase money financing and (b) without limiting KeyBank’s commitment hereunder, any portion of the Facility not funded in connection with the closing of the Acquisition shall be terminated upon such closing.

The provisions set forth in this Commitment Letter relating to the indemnification for expenses and other matters shall survive any closing of the Facility or termination of this Commitment Letter until such terms are fully satisfied and all sums due thereunder are fully paid.

The proposal set forth herein shall be considered withdrawn if for any reason you fail to return to KeyBank by 5:00 P.M. (Eastern time) on May 15, 2015 (the “Expiration Date”) one original of this Commitment Letter signed by Borrower, together with the non-refundable balance of the Underwriting Fee described in the Fee Letter.  The Underwriting Fee is consideration for the issuance of this commitment and the substantial services that KeyBank has rendered and will render in structuring the Facility.  The $100,000 portion of the Underwriting Fee due and payable upon the execution and delivery of the Mandate Documents by KeyBank and KeyBanc pursuant to the terms of the Fee Letter is fully earned as of the date of such execution and delivery and is nonrefundable under any circumstances, whether or not the Facility closes.

If the foregoing is in accordance with your understanding, please accept this Commitment Letter by signing where indicated in the space below and returning it to KeyBank on or prior to the Expiration Date.  This Commitment Letter when fully executed and delivered as provided herein supersedes all of the prior letters and communications from KeyBanc or KeyBank to you, if any, regarding the Facility.

[Remainder of Page Intentionally Left Blank]

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Very truly yours,

KeyBank National Association

Acknowledged and agreed to as of April 27, 2015.

CyrusOne LP

[Signature Page to Commitment Letter (CyrusOne)]

CyrusOne

Confidential Senior Unsecured Bridge Loan

Term Sheet

April 14, 2015

This Term Sheet is delivered in connection with the Commitment Letter, Fee Letter and Mandate Letter, each dated April 14, 2015 (collectively, the “Mandate Documents”). Capitalized terms used herein and not otherwise defined shall have the meanings given to such terms in the Mandate Documents and the Credit Agreement, dated as of October 9, 2014, among the Borrower, KeyBank National Association (“KeyBank”), the other lending institutions party thereto as “Lenders” from time to time, KeyBank, as the Administrative Agent (in its capacity as administrative agent (the “Administrative Agent”), JPMorgan Chase Bank, N.A., as Syndication Agent, KeyBanc Capital Markets (“KeyBanc”) and J.P. Morgan Securities LLC, TD Securities (USA) LLC, Barclays Bank plc and RBC Capital Markets, as the Joint Bookrunners (as amended to date, the “Existing Credit Agreement”).

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(1)  The Lead Arranger expects to state that the Acquisition Agreement (including all disclosure schedules and exhibits thereto) is satisfactory in connection with the final execution of the Acquisition Agreement.

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EXHIBIT A - Definitions

Capitalized Terms not further defined within this term sheet shall refer to the defined terms illustrated within the Credit Agreement entered into by the Borrower on October 9, 2014 and the Mandate Documents.

Target:         Cervalis Holdings, LLC

Target Acquisition: Cervalis Holdings, LLC which is a premier provider of high quality datacenter services to large enterprises in NY metro market.  The assets include four, world-class, Tier 3+ data center facilities and two standalone work area recovery facilities carefully sited to serve across the New York metropolitan region.

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