CONSENT AGREEMENT

Exhibit 10.51

CONSENT AGREEMENT

(MEZZANINE LOAN)

THIS CONSENT AGREEMENT (the “ Agreement ”) is executed and entered into as of October 27, 2004 by and among FIVE MILE CAPITAL POOLING INTERNATIONAL II, LLC, having an address at 4 Stamford Plaza, Stamford, Connecticut 06902 (“ Lender ”), and GLOBAL MARSH MEMBER, LLC, a Delaware limited liability company (“ Global Marsh Member ”), GLOBAL MARSH LIMITED PARTNER, LLC, a Delaware limited liability company (“ Mortgage Borrower LP ”, and together with Global Marsh Member, collectively, “ Borrower ”), GLOBAL INNOVATION PARTNERS, LLC, a Delaware limited liability company (“ Original Guarantor ”), DIGITAL REALTY TRUST, L.P., a Maryland limited partnership (“ Replacement Guarantor ”), each having an address c/o GI Partners, 2730 Sand Hill Road, Suite 280, Menlo Park, California 94025 Attn: Mr. Richard Magnuson and Mr. Michael Foust (),. The term “ Effective Date ” as used in this Agreement shall mean the date upon which this Agreement has been signed and delivered by both Lender and Borrower.

RECITALS

A. On August 18, 2003, German American Capital Corporation, a Maryland corporation (“ Original Lender ”), made a loan (“ Loan ”) in the original principal amount of $22,000,000.00 to Borrower pursuant to the terms of that certain Mezzanine Loan and Security Agreement dated as of August 18, 2003 by and among between Original Lender and Borrower, as amended by that certain Omnibus First Amendment to Mezzanine Loan Documents dated as of November 10, 2003 by and among Borrower and Original Lender (as it has been, and may hereinafter be, amended, the “ Loan Agreement ”; all capitalized terms used herein and not defined shall have the meanings ascribed to such terms in the Loan Agreement).

B. Original Lender has previously assigned to Lender the Loan Agreement the other loan documents described on Exhibit A attached hereto and any other loan document described in the Loan Agreement evidencing and/or securing the Loan (collectively, the “ Loan Documents ”). The Loan is secured by, among other things, that certain Pledge and Security Agreement dated as of August 18, 2003 from Borrower to Lender (as the same may be amended, modified or supplemented from time to time, the “ Pledge ”) and the other Loan Documents.

C. Global Marsh Property Owner, L.P., a Texas limited partnership (“ Mortgage Borrower ”) is the owner of certain real property commonly known as: (a) Ardenwood Corporate Park located in the City of Fremont, County of Alameda, State of California (the “ Ardenwood Corporate Park Property ”), (b) 2334 Lundy Place located in the City of San Jose, County of Santa Clara, State of California (the “ 2334 Lundy Place Property ”) and (c) 2440 Marsh Lane located in the City of Carrollton, County of Dallas, State of Texas (the “ 2440 Marsh Lane Property ” and together with Ardenwood Corporate Park Property and the 2334 Lundy Place Property, collectively, the “ Properties ”), which Properties are more particularly described in the Loan Agreement.

D. In connection with the proposed initial public offering (the “ IPO ”) of the shares in Digital Realty Trust, Inc., a Maryland real estate investment trust (the “ REIT ”), and the

sole general partner of Replacement Guarantor, Original Guarantor desires to transfer (“ Transfer ”) all of its membership interests in Global Marsh Member which is (i) the sole member of Mortgage Borrower LP, which is the 99.5% limited partner of Mortgage Borrower, and (ii) the sole member of Global Marsh General Partner, LLC, a Delaware limited liability company, which is the 0.5% general partner of Borrower (“ Mortgage Borrower GP ”), to Replacement Guarantor.

E. The Loan Documents prohibit the Transfer without first obtaining Lender’s written consent; and

F. Lender has agreed to consent to the Transfer subject to the terms and conditions hereinafter set forth.

NOW, THEREFORE, in consideration of the foregoing premises and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto, intending to be legally bound hereby, agree as follows:

Article I.

BORROWER ACKNOWLEDGMENTS, WARRANTIES,

REPRESENTATIONS AND COVENANTS

As a material inducement to Lender to enter into this Agreement and to consent to the Transfer, Borrower (prior to the consummation of the Transfer) acknowledges, represents, warrants, covenants and agrees to and with Lender as follows:

1.1 Authority of Borrower Prior to Transfer . Prior to the Transfer:

(a) Mortgage Borrower is a duly organized, validly existing limited partnership in good standing under the laws of the State of Texas and is duly authorized to transact business in the State of California. Mortgage Borrower GP is the sole general partner of Mortgage Borrower, and Mortgage Borrower LP is the sole limited partner of Mortgage Borrower.

(b) Mortgage Borrower GP is a duly organized, validly existing limited liability company in good standing under the laws of the State of Delaware and is duly authorized to transact business in the States of Texas and California. Global Marsh Member is the sole member of Mortgage Borrower GP.

(c) Mortgage Borrower LP is a duly organized, validly existing limited liability company in good standing under the laws of the State of Delaware and is duly authorized to transact business in the States of Texas and California. Global Marsh Member is the sole member of Mortgage Borrower LP. Global Marsh Member, acting alone without the joinder of any other party, has the power and authority to execute this Agreement on behalf of and to duly bind Mortgage Borrower LP under this Agreement. The execution and delivery of, and performance under, this Agreement by Mortgage Borrower LP has been duly and properly authorized pursuant to all requisite limited liability company action and will not (i) violate any provision of any law, rule, regulation, order, writ, judgment, injunction, decree, determination or award presently in effect having applicability to Mortgage Borrower LP or the certificate of

incorporation, the operating agreement or any other organizational document of Mortgage Borrower LP or (ii) result in a breach of or constitute or cause a default under any indenture, agreement, lease or instrument to which Mortgage Borrower LP is a party or by which any of the Collateral may be bound or affected.

(d) Global Marsh Member is a duly organized, validly existing limited liability company in good standing under the laws of the State of Delaware and is duly authorized to transact business in the States of Texas and California. Original Guarantor is the sole member of Global Marsh Member. Original Guarantor, acting alone without the joinder of any other party, has the power and authority to execute this Agreement on behalf of and to duly bind Global Marsh Member under this Agreement. The execution and delivery of, and performance under, this Agreement by Global Marsh Member has been duly and properly authorized pursuant to all requisite limited liability company action and will not (i) violate any provision of any law, rule, regulation, order, writ, judgment, injunction, decree, determination or award presently in effect having applicability to Global Marsh Member or the certificate of incorporation, the operating agreement or any other organizational document of Global Marsh Member or (ii) result in a breach of or constitute or cause a default under any indenture, agreement, lease or instrument to which Global Marsh Member is a party or by which any of the Collateral may be bound or affected.

(e) Original Guarantor is a duly organized, validly existing limited liability company in good standing under the laws of the State of Delaware and is duly authorized to transact business in the States of Texas and California. Global Innovation Manager, LLC, a Delaware limited liability company (“ Manager ”) is the Manager of Original Guarantor. Manager, acting alone without the joinder of any other party, has the power and authority to execute this Agreement on behalf of and to duly bind Original Guarantor under this Agreement. The execution and delivery of, and performance under, this Agreement by Original Guarantor has been duly and properly authorized pursuant to all requisite limited liability company action and will not (i) violate any provision of any law, rule, regulation, order, writ, judgment, injunction, decree, determination or award presently in effect having applicability to Original Guarantor or the certificate of formation, the limited liability company agreement or any other organizational document of Original Guarantor or (ii) result in a breach of or constitute or cause a default under any indenture, agreement, lease or instrument to which Original Guarantor is a party or by which any of the Collateral may be bound or affected.

(f) Manager is a duly organized, validly existing limited liability company in good standing under the laws of the State of Delaware and is qualified to do business in the States of Texas and California. Richard Magnuson and Michael Foust are authorized signatories (each, an “ Original Guarantor Authorized Person ”) for Manager. Either Original Guarantor Authorized Person, acting alone without the joinder of the other or of any other party, has the power and authority to execute this Agreement on behalf of and to duly bind Manager under this Agreement. The execution and delivery of, and performance under, this Agreement by Manager has been duly and properly authorized pursuant to all requisite limited liability company action and will not (i) violate any provision of any law, rule, regulation, order, writ, judgment, injunction, decree, determination or award presently in effect having applicability to Manager or the certificate of formation, the limited liability company agreement or any other organizational document of Manager or (ii) result in a breach of or constitute or cause a default

under any indenture, agreement, lease or instrument to which Manager is a party or by which any of the Collateral may be bound or affected.

(g) The organizational documents of Borrower, Mortgage Borrower GP, Mortgage Borrower, Original Guarantor and Manager (collectively, “ Original Mezzanine Borrower Parties ”) have not been modified (other than to reflect the Transfers) since loan origination.

1.2 Loan Documents . The Loan Documents to which Borrower and/or Original Guarantor is a party constitute the valid and legally binding obligations of Borrower and Original Guarantor, enforceable against Borrower, Original Guarantor, the Collateral and the Properties in accordance with their terms, except to the extent that such enforcement may be limited by applicable bankruptcy, insolvency, reorganization or other similar laws affecting the rights of creditors generally or general principles of equity. The Pledge is a valid first lien on the Pledged Collateral for the full unpaid principal amount of the Loan and all other amounts stated in the Loan Documents. Borrower and Original Guarantor have no defenses, setoffs, claims, counterclaims or rights of defense, rights of setoff or counterclaim, whether legal, equitable or otherwise, to the obligations evidenced by or set forth in the Loan Agreement, the Note (as defined in Exhibit A ), the Pledge or any of the other Loan Documents or causes of action of any kind or nature whatsoever against Lender or any of Lender’s officers, directors, servicers or predecessors in interest (collectively, “ Lender Parties ”) with respect to (i) the Loan, (ii) any of the Loan Documents to which Borrower is a party, (iii) the Debt (as such term is defined in the Loan Agreement), (iv) any other documents or instruments now or previously evidencing, securing or in any way relating to the Loan, (v) the administration or funding of the Loan, (vi) the Collateral or (vii) the development, operation or financing of the Properties.

1.3 Affirmation of Obligations of Borrower . Borrower hereby affirms the existence and the validity of its and Original Guarantor’s respective obligations, as applicable, and the other provisions in the Loan Agreement, the Note, the Pledge and the other Loan Documents in accordance with their respective terms and conditions. Borrower further confirms that the Transfer shall not affect its or Original Guarantor’s obligations to, and Borrower agrees to continue, and at and after the Transfer, to abide by and be bound by all of the terms of the Loan Documents to which it is a party, or upon the Transfer has become a party, including but not limited to, the representations, warranties, covenants, assurances and indemnifications in the respective agreements to which it is a party.

1.4 No Default . To the best of Borrower’s knowledge, there currently exist no Defaults nor Events of Default under the Loan Documents.

1.5 Liens . There are no: (a) subordinate liens of any kind covering or relating to the Properties or the Collateral and Borrower has not received written notice, and has no actual knowledge of, any mechanics’ liens or liens for unpaid taxes or assessments encumbering the Pledged Collateral or any of the Properties other than those not yet due and payable, nor has notice of a lien or notice of intent to file a lien been received by Borrower, or (b) pending or, to the best of knowledge of Borrower, threatened (in writing) condemnation proceedings or annexation proceedings affecting the Pledged Collateral or any of the Properties, nor any agreements to convey the Pledged Collateral or any portion of any of the Properties, or any rights thereto to any person or entity, including, without limitation, any government or governmental agency.

1.6 Financial Statements . The financial information regarding Borrower and the Properties, including, but not limited to the rent roll for each of the Properties (collectively, the “ Rent Rolls ”) supplied by, or on behalf of, Borrower in connection with Borrower’s request for Lender consent to the Transfer (collectively, the “ Financial Information ”) were, in all material respects, true and correct on the dates they were supplied to Lender, and since such date no material adverse change in the financial condition of Borrower or the Properties has occurred, and there is no pending or, to the best knowledge of Borrower, threatened litigation or proceedings of any kind which might materially impair the business or financial condition of Borrower, the Collateral or the Properties. Borrower acknowledges that the Financial Information has been provided to Lender to induce Lender to consent to the Transfer and enter into this Agreement and is being relied upon by Lender for such purposes.

1.7 Legal Proceedings . There is no action, proceeding or investigation pending or, to the best knowledge of Borrower, threatened in writing which questions, directly or indirectly, the validity or enforceability of this Agreement or any of the Loan Documents applicable to Borrower, or any action taken or to be taken pursuant hereto or thereto, or which might result in any material adverse change in the condition (financial or otherwise) or business of Borrower.

1.8 Acknowledgement of Indebtedness . To Borrower’s knowledge, Borrower confirms that, and by its execution hereof, Lender confirms that to Lender’s actual knowledge, as of September 30, 2004, the outstanding principal balance of the Note was $22,000,000. Borrower acknowledges and agrees that the Loan, as evidenced and secured by the Loan Documents and described above, is a valid and existing indebtedness payable by Borrower to Lender. Lender further confirms that to its actual knowledge, it has not issued any written notices of default to Borrower which have not been cured.

1.9 Rent Rolls . The Rent Rolls contain true, complete and accurate summaries, in all material respects, of all tenant leases affecting each of the Properties (“ Leases ”) as of the date of each Rent Roll.

1.10 Leases . The Leases are the only leases affecting the Properties and are currently in full force and effect, and unless otherwise indicated on the Rent Rolls, are unmodified. Borrower has not been notified in writing and has no actual knowledge of any landlord default in any material respect under any of the Leases. The rents under the Leases shown on the Rent Roll are true and correct. Borrower has not received any prepaid rents for more than one month in advance or given any concessions for free or reduced rent under the Leases, except as provided in the Leases. All tenants at the Properties are currently in possession of their leased premises, and, to the best of Borrower’s knowledge, operating businesses therefrom.

1.11 Bankruptcy . None of Original Mezzanine Borrower Parties has any intent to (a) file any voluntary petition under any Chapter of the Bankruptcy Code, Title 11, U.S.C.A. (“Bankruptcy Code”), or in any manner to seek any proceeding for relief, protection,

reorganization, liquidation, dissolution or similar relief for debtors (“ Debtor Proceeding ”) under any local, state, federal or other insolvency law or laws providing relief for debtors or (b) directly or indirectly to intentionally cause any involuntary petition under any Chapter of the Bankruptcy Code to be filed against any of Original Mezzanine Borrower Parties, or (c) directly or indirectly to intentionally cause any of the Collateral or Properties or any portion or any interest of Borrower in the Collateral or any of the Properties to become the property of any bankrupt estate or the subject of any Debtor Proceeding.

1.12 Single Purpose Entity Status . None of the representations set forth in Section 4.1.19 of the Loan Agreement are untrue or incorrect in any material respect.

1.13 No Modification . After the Transfer, all of the terms, covenants and conditions of the Loan Documents shall continue in full force and effect unmodified, except that Section 5.2.2 of the Loan Agreement shall not be applicable to Guarantor (as such term is defined in the Loan Agreement) upon Replacement Guarantor’s assumption of Original Guarantor’s rights and obligations under the Loan Documents and its execution and delivery of that certain Guarantee of Recourse Obligations (Mezzanine) and that certain Environmental Indemnity (Mezzanine). The Transfer will not cause any breach or default of any of the terms, conditions, covenants, agreements or any of the other provisions of the Loan Documents. Except as set forth in this Agreement, the execution and delivery of this Agreement or the consummation of the Transfer shall not, in any way, release, diminish, waive, lessen or compromise Borrower’s or Original Guarantor’s obligations to Lender under the Loan Documents.

1.14 Reaffirmations and Release . Borrower and Original Guarantor reaffirm, affirm and confirm, to the best of their knowledge, the truth and accuracy of all representations and warranties set forth in the Loan Documents as if made on the date hereof. Borrower acknowledges and agrees that nothing contained in this Agreement, nor the Transfer, shall release Borrower from any of its obligations, agreements duties and liabilities under the Loan Documents (the “ Guaranteed Obligations ”); provided, however, by its execution and delivery hereof, Lender hereby agrees that, upon the consummation of the IPO, Original Guarantor shall be deemed to have been released from its obligations under the Guaranty (as defined in Exhibit A attached hereto) and the Environmental Indemnity (as defined in Exhibit A attached hereto) pursuant to the terms of the Joinder of Original Guarantor attached hereto.

1.15 Assets of Borrower . The only assets of Borrower are (i) the Collateral and (ii) its limited liability company membership interest in and to Mortgage Borrower LP and Mortgage Borrower GP.

1.16 Same Indebtedness; Priority of Liens Not Affected . This Agreement and the execution of other documents contemplated hereby do not constitute the creation of a new debt or the extinguishment of the debt evidenced by the Loan Documents, nor will they in any way affect or impair the liens and security interests created by the Loan Documents. Borrower agrees that the lien and security interests created by the Pledge continue to be in full force and effect, unaffected and unimpaired by this Agreement and that said liens and security interests shall so continue in their perfection and priority until the Debt is fully discharged.

1.17 Consents . Original Mezzanine Borrower Parties have obtained and provided Lender with true and correct copies of all consents to the Transfer required to be obtained by any Original Mezzanine Borrower Party under any applicable agreement, instrument document, law, rule, or regulation, including, the consent of Mortgage Lender under the Loan Documents (Mortgage).

1.18 Release and Covenant Not To Sue . Borrower on behalf of itself and the other Original Mezzanine Borrower Parties, on behalf of itself and each of its successors and assigns and each of the successors and assigns of the other Original Mezzanine Borrower Parties, remises, releases, acquits, satisfies and forever discharges Lender Parties from any and all manner of debts, accountings, bonds, warranties, representations, covenants, promises, contracts, controversies, agreements, liabilities, obligations, expenses, damages, judgments, executions, actions, inactions, claims, demands and causes of action of any nature whatsoever, at law or in equity, known or unknown, either now accrued or subsequently maturing, which Borrower or any of the other Original Mezzanine Borrower Parties now have or hereafter can, shall or may have by reason of any matter, cause or thing, from the beginning of the world to and including the date of this Agreement, arising out of or relating to (a) the Loan, including, but not limited to, its administration or funding, (b) the Loan Documents, (c) the Debt, (d) any other agreement or transaction between any of the Original Mezzanine Borrower Parties and any of the Lender Parties, (e) the Collateral and (f) the Properties or their development, financing and operation, but excluding any claims or causes of action resulting from or in connection with this Agreement. Borrower on behalf of itself and the other Original Mezzanine Borrower Parties, on behalf of itself and each of its successors and assigns and each of the successors and assigns of the other Original Mezzanine Borrower Parties, covenants and agrees never to institute or cause to be instituted or continue prosecution of any suit or other form of action or proceeding of any kind or nature whatsoever against any of the Lender Parties by reason of or in connection with any of the foregoing matters, claims or causes of action, but excluding any claims or causes of action resulting from or in connection with this Agreement.

1.19 Transfer Documents . Other than those documents listed on Exhibit C attached hereto (the “ Transfer Documents ”), no other documents, instruments, certificates or opinions were executed and/or delivered by Borrower or by any of the other Original Mezzanine Borrower Parties in connection with the Transfer and related to the Collateral.

1.20 Further Assurances . Borrower shall execute and deliver to Lender such agreements, instruments, documents, financing statements and other writings as may be reasonably requested from time to time by Lender to consummate the transactions contemplated by this Agreement.

1.21 UCC Policy . The Eagle 9 UCC Insurance Policy No. E9002885 issued by First American Title Insurance Company remains in full force and effect and the Transfer and the execution and delivery of this Consent do not affect or impair the insurance coverage provided to Lender thereunder.

Article II.

BORROWER ACKNOWLEDGMENTS, WARRANTIES,

REPRESENTATIONS AND COVENANTS

As a material inducement to Lender to enter into this Agreement and to consent to the Transfer, Borrower (after the consummation of the Transfer) acknowledges, represents, warrants, covenants and agrees to and with Lender as follows:

2.1 Authority of Borrower Simultaneously With and After the Transfer . Simultaneously with and after the Transfer:

(a) Mortgage Borrower is a duly organized, validly existing limited partnership in good standing under the laws of the State of Texas and is duly authorized to transact business in the State of California. Mortgage Borrower GP is the sole general partner and Mortgage Borrower LP is the sole limited partner of Mortgage Borrower.

(b) Mortgage Borrower GP is a duly organized, validly existing limited liability company in good standing under the laws of the State of Delaware and is qualified to do business in the States of Texas and California. Global Marsh Member is the sole member of Mortgage Borrower GP.

(c) Mortgage Borrower LP is a duly organized, validly existing limited liability company in good standing under the laws of the State of Delaware and is qualified to do business in the States of Texas and California. Global Marsh Member is the sole member of Mortgage Borrower LP. Global Marsh Member, acting alone without the joinder of any other party, has the power and authority to execute this Agreement on behalf of and to duly bind Mortgage Borrower LP under this Agreement. The execution and delivery of, and performance under, this Agreement by Mortgage Borrower LP has been duly and properly authorized pursuant to all requisite limited liability company action and will not (i) violate any provision of any law, rule, regulation, order, writ, judgment, injunction, decree, determination or award presently in effect having applicability to Mortgage Borrower LP or the certificate of incorporation, the operating agreement or any other organizational document of Mortgage Borrower LP or (ii) result in a breach of or constitute or cause a default under any indenture, agreement, lease or instrument to which Mortgage Borrower LP is a party or by which any of the Collateral may be bound or affected.

(d) Global Marsh Member is a duly organized, validly existing limited liability company in good standing under the laws of the State of Delaware and is qualified to do business in the States of Texas and California. Replacement Guarantor is the sole member of Global Marsh Member. Replacement Guarantor, acting alone without the joinder of any other party, has the power and authority to execute this Agreement on behalf of and to duly bind Global Marsh Member under this Agreement. The execution and delivery of, and performance under, this Agreemen