<PAGE>
                                                                    EXHIBIT 10.4

                               100 FIFTH AVENUE
                            WALTHAM, MASSACHUSETTS

                         AMENDED AND RESTATED SUBLEASE
                               BASIC INFORMATION


DATE:                   July 6, 1999

SUBLESSOR:              Innovation Associates, Inc., a
                        Massachusetts corporation

SUBLESSEE:              StorageNetworks, Inc., a
                        Delaware corporation

SUBLEASED               Sixth (6th) floor

PREMISES:               100 Fifth Avenue
                        Waltham, Massachusetts

NET RENTABLE
AREA OF SUBLEASED
PREMISES:               21,000 square feet

TERM COMMENCEMENT:      August 1, 1999; existing Sublease and License
                        Agreement will remain in effect until August 1,
                        1999

TERM EXPIRATION:        January 14, 2001

BASE RENT:              $40,250 per month

SECURITY DEPOSIT:       $120,750

SUBLESSEE'S AND
SUBLESSOR'S ADDRESS
FOR NOTICES:            See Section 15

EXHIBITS:               Exhibit A - Copy of Master Lease
                        Exhibit B - Diagram of Subleased Premises
                        Exhibit C - Form of Letter of Credit
                        Exhibit D - Letter from Sublessee to Arthur D. Little,
                        Inc.
<PAGE>

                         AMENDED AND RESTATED SUBLEASE
                         -----------------------------

     This Amended and Restated Sublease (this "Sublease") is entered into as of
the 6th day of July, 1999, by and between Innovation Associates, Inc.
("Sublessor") and StorageNetworks, Inc. ("Sublessee") as a sublease under that
certain Lease (the "Master Lease") dated December 1995, between Prospect Hill
Acquisition Trust ("Master Lessor"), as Lessor, and Innovation Associates, Inc.,
as Lessee. A copy of the Master Lease is attached hereto as Exhibit A.
                                                            ----------

     WHEREAS, pursuant to that certain Sublease and License Agreement (the
"Agreement") dated as of April 9, 1999, Sublessee subleased from Sublessor 9,036
net rentable square feet on the 6th floor of the premises at 100 Fifth Avenue,
Waltham, Massachusetts, and licensed from Sublessor the use of 2,274 net
rentable square feet on the 6th floor of such premises;

     WHEREAS, Sublessee and Sublessor desire to amend and restate the Agreement
in order that Sublessee shall sublease from Sublessor the entire premises leased
by Sublessor at 100 Fifth Avenue, Waltham, Massachusetts pursuant to the Master
Lease, on the terms and conditions set forth below:

                                  WITNESSETH
                                  ----------

     Sublessor hereby subleases to Sublessee and Sublessee hereby subleases from
Sublessor the area and space described in Section I below as the Subleased
Premises for the term and subject to the terms, covenants, agreements, and
conditions hereinafter set forth, to each and all of which Sublessor and
Sublessee hereby mutually agree, and further subject to the written approval of
Master Lessor.

1. The "Subleased Premises" consist of 21,000 square feet of net rentable area
   on the 6th floor of 100 Fifth Avenue, Waltham, Massachusetts, as shown on
   Exhibit B. Such square footage has been computed in the same manner as
   ---------
   provided in the Master Lease.

2. All of the terms, covenants, and conditions of the Master Lease, insofar as
   they relate to the Subleased Premises, are hereby incorporated by reference
   in this Sublease and made a part hereof as if the same were set forth in full
   in this Sublease, except: (a) the basic lease provisions applicable to this
   Sublease shall be as set forth on the first page hereof; (b) the base rent
   and additional rent payable by Sublessee to Sublessor in respect of the
   Subleased Premises shall be in the amount and shall be payable as provided in
   Section 4 hereof; (c) for defaults in the payment of rent, additional rent
   (including Sublessee's share of Operating Expenses and Real Property Taxes
   (each as defined in the Master Lease) increases), or any other amounts due
   under this Sublease, the grace period shall be five (5) days after the due
   date of such payment (without any requirement of notice); (d) for defaults
   other than payment defaults, the grace period shall be five (5) days less
   than that provided for Sublessor, as lessee, under the Master Lease; (e)
   Sublessor's Extension Option (as described in Exhibit D of the Master Lease)
   shall not operate for the benefit of Sublessee and may not be enforced by
   Sublessee; and (f) the term "Landlord" as used in the Master Lease shall
<PAGE>

   mean Sublessor hereunder and the term "Tenant" under the Master Lease shall
   mean Sublessee hereunder.

   In the event of any default on the part of Sublessee under any of the terms,
   covenants, and conditions of this Sublease (including those terms, covenants,
   and conditions of the Master Lease incorporated by reference herein),
   Sublessor shall have the same rights and remedies against Sublessee under
   this Sublease as are available to Master Lessor against Sublessor, as lessee,
   under the Master Lease.

   Sublessee represents to Sublessor that it has read the Master Lease and that
   it is familiar with the contents thereof. Sublessee covenants and agrees that
   it will perform, comply with, and observe all of the terms, covenants, and
   conditions contained in the Master Lease insofar as they relate to the use
   and occupancy of the Subleased Premises, except for those provisions made
   inapplicable by the express provisions of this Sublease or superseded by the
   context of the specific provisions hereof.

   Sublessor acknowledges that Sublessee is negotiating with Master Lessor to
   extend the term of Sublessor's tenancy in the Subleased Premises. To that
   end, Sublessor will cooperate with Sublessee and Master Lessor by executing
   relevant documents provided, however, that Sublessor will not assume any
   obligations, financial or otherwise, other than those that Sublessor is
   otherwise obligated to perform pursuant to the Master Lease and the Sublease.

3. The Sublease term shall commence on August 1, 1999 and shall end on January
   14, 2001, or on such earlier date upon which said term may expire or be
   terminated pursuant to a termination of the Master Lease or any of the
   conditions or limitations or other provisions of this Sublease or pursuant
   to law. Notwithstanding the foregoing or any other provision of this Sublease
   to the contrary, until such August 1 commencement date, the terms and
   provisions of the Agreement shall remain in full force and effect. Provided
   that the Master Lessor has approved this Sublease, Sublessee shall be allowed
   access to the Subleased Premises on and after July 15, 1999, for the purpose
   of installing Sublessee's telephone systems and performing related work,
   provided that such work shall not disrupt Sublessor's business and Sublessee
   shall provide at least 24 hours' prior notice to Sublessor of Sublessee's
   desire to enter into the Subleased Premises for such purposes.

4. Sublessee shall pay to Sublessor during the term base rent for the Subleased
   Premises in the amount of $40,250 per month, payable in advance on the
   fifteenth day of each month. Payments of base rent shall not commence until
   the date that this Sublease has been signed by both parties and approved by
   the Master Lessor. The base rent payable hereunder shall be increased by the
   amount, if any, of any increase in Operating Expenses and Real Property Taxes
   (as such terms are defined in the Master Lease) allocable to the Subleased
   Premises over the Base Year. Sublessee and Sublessor agree that the
   proportionate share of Operating Expenses and Real Estate Taxes allocable to
   the Subleased Premises is 14.0%. The term "Base Year" shall mean calendar
   year 1999 for purposes of computing Operating Expenses, and fiscal year 1999
   for purposes of computing Real Property Taxes. Sublessor shall notify
   Sublessee in writing as to any such increase, and the base rent payable under
   this Sublease shall be deemed to be amended to reflect any such increase.
   Sublessor and Sublessee agree that the base rent, as the same may be
   increased pursuant to the foregoing sentence, shall be

                                       3
<PAGE>


    deemed to include a pro rata share based on the square footage of the
    Subleased Premises of any amounts payable by Sublessor to Master Lessor for
    Operating Expenses or Real Property Taxes in respect of the Subleased
    Premises pursuant to the Master Lease, and that Sublessee shall not be
    obligated to pay to Sublessor a pro rata portion of Operating Expenses or
    Real Property Taxes, or any escalations thereof, except in accordance with
    this Section 4. Notwithstanding the foregoing, Sublessee shall be
    responsible for paying all charges for electricity related to the Subleased
    Premises. Such electricity shall be separately metered at Sublessor's sole
    cost and expense.

5.  Upon the execution of this Sublease, Sublessee shall pay and Sublessor shall
    hold one hundred twenty thousand seven hundred fifty dollars ($120,750) as
    security (the "Security Deposit) for the payment of all rent and other sums
    of money payable under the terms of this Sublease and for the faithful
    performance by Sublessee of each of its other obligations hereunder. Sixty
    thousand dollars ($60,000) (of which Sublessor currently is holding $51,957)
    of the Security Deposit shall be paid to Sublessor by check, subject to
    collection. At Sublessee's option, the balance of the Security Deposit
    ($60,750) shall be paid to Sublessor by check, subject to collection, or
    shall be secured by an irrevocable Letter of Credit from a Massachusetts
    bank or other financial institution reasonably acceptable to Sublessor, of
    even date and execution herewith, in the form of Exhibit C attached hereto
                                                     ---------
    and made a part hereof (together with any additional or replacement letter
    of credit, the "Letter of Credit"). Sublessee shall pay any and all fees
                    ----------------
    charged by the issuing bank in respect of the Letter of Credit. If the bank
    on which the Letter of Credit is drawn elects not to renew the Letter of
    Credit or is declared insolvent or placed into conservatorship or
    receivership, Sublessee shall, within ten (10) days after such election or
    event, replace the Letter of Credit with a like Letter of Credit from
    another bank or financial institution reasonably acceptable to Sublessor. In
    the event of an Event of Default (as defined in the Master Lease, subject to
    the terms hereof), Sublessee hereby authorizes Sublessor, at Sublessor's
    election and with or without terminating this Sublease and without prejudice
    to any other right or remedy Sublessor may have, to apply all or any portion
    of the Security Deposit necessary to remedy such default, including by
    drawing on the Letter of Credit. The order in which Sublessor applies the
    proceeds of the cash portion of the Security Deposit and the proceeds of the
    Letter of Credit shall be determined by Sublessor from time to time in its
    sole discretion. If all or any of the cash portion of the Security Deposit
    is so applied, Sublessee, upon demand by Sublessor, shall immediately
    deposit with Sublessor an amount equal to the amount of the cash portion of
    the Security Deposit so applied. If all or any of the proceeds of the Letter
    of Credit is so applied, Sublessee, upon demand by Sublessor, shall
    immediately arrange for the issuance of an additional or replacement Letter
    of Credit in an amount equal to the amount of the proceeds of the then-
    outstanding, Letter of Credit so applied. The cash portion of the Security
    Deposit or any portion thereof not previously applied by Sublessor shall be
    returned to Sublessee within thirty (30) days after the expiration or
    earlier termination (other than a termination resulting from Sublessee's
    default) of the term of this Sublease, provided that Sublessee shall have
    fully vacated the Subleased Premises and such premises are left in the same
    condition as on the term commencement date, reasonable wear and tear
    excepted. Notwithstanding any provision of this Sublease to the contrary,
    for purposes of the foregoing sentence, the term commencement date with
    respect to the 11,310 square feet of the Subleased Premises occupied by
    Sublessee on the date hereof shall be April 15, 1999. The intention of the
    parties is that the Security Deposit shall secure Sublessor not only as to
    default by Sublessee, but also shall secure Sublessor from any deficiency in
    rent or other charges payable to Sublessor by Sublessee during the term of
    this Sublease.

6.  The Subleased Premises shall be delivered to Sublessee in "as is" condition,
    provided that Sublessor shall vacate the Subleased Premises in broom-clean
    condition and remove its personal property and signs from the Subleased
    Premises prior to Sublessee's occupancy thereof. Any improvements, changes,
    or additions made by Sublessee shall be subject to the prior written consent
    of Sublessor and Master Lessor in accordance with the provisions of the
    Master Lease and shall be made at Sublessee's expense. Sublessor hereby
    consents to any work proposed to be performed by Sublessee provided that
    Master Lessor consents thereto. Master Lessor's consent to this Sublease
    shall not be or be deemed a consent to such work in the Subleased Premises.
    Any such work by Sublessee in the Subleased Premises and Master Lessor's
    consent thereto shall be in accordance with Section 7.3 of the Master Lease,
    except that Section 7.3(a) with respect to Permitted Alterations (as defined
    in the Master Lease) shall not be applicable to Sublessee. Sublessor
    acknowledges that there are no alterations or improvements in the Subleased
    Premises as of the date hereof that must be removed upon the expiration of
    the Master Lease, other than alterations or improvements made by Sublessee
    (including, without limitation, the alterations and improvements described
    in that certain letter dated June 7, 1999 from Sublessee to Arthur D.
    Little, Inc., a copy of which is attached hereto as Exhibit D and made a
                                                        ---------
    part hereof).

                                       4
<PAGE>

7.  Sublessee shall not voluntarily, involuntarily, or by operation of law,
    assign, transfer, sublease, mortgage, pledge, or encumber (hereinafter
    referred to as transfer) this Sublease or any interest herein without the
    prior written consent of Sublessor, which shall not be unreasonably
    withheld, and without the prior written consent of Master Lessor. A consent
    to a transfer shall not release Sublessee of any of its obligations
    hereunder or be deemed to be a consent to any subsequent transfer. Any
    transfer without written consent will be null and void. Any dissolution,
    merger, consolidation, or other reorganization of Sublessee or the sale or
    other transfer or disposition (in a single transaction or a series of
    transactions) of a controlling percentage of the stock of Sublessee shall
    constitute a transfer of this Sublease.

8.  Sublessee shall maintain insurance in accordance with the Master Lease. Such
    policies of insurance shall name Sublessor and Master Lessor and its
    property manager (currently, The Nelson Companies, Ltd.) as an additional
    insured, shall contain a cross liability endorsement, and shall provide that
    the same may not be cancelled except upon 30 days prior written notice to
    Sublessor and Master Lessor and its property manager. Sublessee shall
    provide Sublessor and Master Lessor and its property manager with a
    certificate or certificates of said policies. Sublessee agrees that such
    insurance shall not be deemed to limit its liability under this Sublease.

9.  To the fullest extent permitted by law, Sublessee hereby agrees to indemnify
    and hold harmless and defend Sublessor from and against any and all actions,
    claims, demands, damages, losses, liabilities, costs, and expenses
    (including reasonable attorneys' fees) asserted against, imposed upon, or
    incurred by Sublessor by reason of (a) any violation of any of the terms,
    covenants, or conditions of the Master Lease or this Sublease caused,
    suffered, or permitted by Sublessee, its agents, servants, employees, or
    invitees, and (b) any damage or injury to persons or property occurring upon
    or in connection with the use or occupancy of the Subleased Premises, except
    to the extent caused by the negligence or willful misconduct of Sublessor,
    its agents, servants, employees, or invitees. Notwithstanding anything in
    this Sublease to the contrary, including but not limited to this Section 9,
    Sublessee will indemnify Master Lessor to the same extent as Sublessor is
    obligated to indemnify Master Lessor under the Master Lease.

10. As between the parties hereto, Sublessor agrees to observe and perform the
    terms, covenants and conditions on its part to be observed and performed
    hereunder and to use diligent efforts to cause Master Lessor to observe and
    perform those applicable terms, covenants and conditions to be observed and
    performed by Master Lessor under the Master Lease with respect to the
    Subleased Premises. Sublessee covenants and agrees that Sublessee will not
    do anything which would constitute a default under the Master Lease or omit
    to do anything which Sublessee is obligated to do under the terms of this
    Sublease and which would constitute a default under the Master Lease.
    Sublessor covenants and agrees to pay the rent and any additional rent
    payable as required under the Master Lease and will not do anything or omit
    to do anything which Sublessor is obligated to do under the terms of the
    Master Lease and which would constitute a default under the Master Lease.

    Sublessor shall not be liable to Sublessee for Master Lessor's negligence or
    misconduct or breach of the Master Lease. If Master Lessor shall default in
    any of its obligations to Sublessor with respect to the Subleased Premises,
    Sublessee shall be entitled to participate with Sublessor in the enforcement
    of Sublessor's rights against Master Lessor with respect to the Subleased
    Premises, but except as hereinafter expressly provided, Sublessor shall have
    no obligation to bring any action or proceeding or to take any steps to
    enforce Sublessor's rights against Master Lessor. If, after written request
    from Sublessee, Sublessor shall unreasonably fail or refuse to take
    appropriate action for the enforcement of Sublessor's rights against Master
    Lessor with respect to the Subleased Premises, Sublessee shall have the
    right to take such action in its own name and at its own expense, and for
    that purpose, and only to such extent, all of the rights of Sublessor under
    the Master Lease shall be and hereby are conferred upon and assigned to
    Sublessee and Sublessee shall be and is hereby subrogated to such rights to
    the extent that the same shall apply to the Subleased Premises, provided and
    to the extent that such action against Master Lessor in Sublessee's name
    shall be barred by reason of lack of privity of contract. If Sublessor shall
    take, or participate in, or shall be requested to participate or assist in
    any action in the enforcement of Sublessee's rights against Master Lessor,
    Sublessee agrees to reimburse Sublessor for all expenses reasonably incurred
    by Sublessor, including without limitation, the attorney's fees of
    Sublessor. Sublessee hereby agrees to indemnify and hold harmless and defend
    Sublessor from and against any and all damages, claims, and liabilities to
    others resulting or allegedly resulting from any action or proceeding taken
    or instituted by Sublessee (or by Sublessor at Sublessee's request) pursuant
    to this section whether or not Sublessor joins in the same.

                                       5
<PAGE>

11. Sublessor shall promptly request any necessary consents and approvals from
    Master Lessor for the parties to enter into this Sublease and shall provide
    reasonable written evidence thereof to Sublessee as a condition precedent to
    the commencement of this Sublease.

12. Sublessee hereby represents and warrants to Sublessor that it has not dealt
    with any broker or agent in connection with this Sublease other than The
    Nelson Companies, whose fee shall be paid in full by Sublessor. Sublessor
    hereby represents and warrants to Sublessee that it has not dealt with any
    broker or agent in connection with this Sublease other than The Nelson
    Companies, whose fee shall be paid in full by Sublessor. Each of Sublessee
    and Sublessor agrees to indemnify and hold harmless the other against any
    claim by any broker or agent arising out of a breach of their respective
    representations and warranties in this Section 12.

13. This Sublease, together with those provisions of the Master Lease applicable
    hereto, contains all of the covenants, agreements, terms, provisions,
    conditions, warranties and understandings relating to the leasing of the
    Subleased Premises and Sublessor's obligations in connection therewith, and
    neither Sublessor nor any agent or representative of Sublessor has made or
    is making, and Sublessee in executing and delivering this Sublease is not
    relying upon, any warranties, representations, promises or statements
    whatsoever, except to the extent expressly set forth in this Sublease. The
    failure of Sublessee or Sublessor to insist in any instance upon the strict
    keeping, observance or performance of any covenant, agreement, term,
    provision or condition of this Sublease or to exercise any election herein
    contained shall not be construed as a waiver or relinquishment for the
    future of such covenant, agreement, term, provision, condition or election,
    but the same shall continue and remain in full force and effect. Except as
    expressly provided in Section 4 hereof, no waiver or modification of any
    covenant, agreement, term provision or condition of this Sublease shall be
    deemed to have been made unless expressed in writing and signed by Master
    Lessor, Sublessee and Sublessor. No surrender of possession of the Subleased
    Premises or of any part thereof or of any remainder of the term of this
    Sublease shall release Sublessee from any of its obligations hereunder
    unless accepted by Sublessor in writing. The receipt and retention by
    Sublessor of monthly base rent or additional rent from anyone other than
    Sublessee shall not be deemed a waiver of the breach by Sublessee of any
    covenant, agreement, term or provision of this Sublease, or as the
    acceptance of such other person as a tenant, or as a release of Sublessee
    from the further keeping, observance or performance by Sublessee of the
    covenants, agreements, terms, provisions and conditions herein contained.
    The receipt and retention by Sublessor of monthly base rent or additional
    rent with knowledge of the breach of any covenant, agreement, term,
    provision or condition herein contained shall not be deemed a waiver of such
    breach.

14. The obligations of this Sublease shall bind and benefit the successors and
    permitted assigns of the parties with the same effect as if mentioned in
    each instance where a party hereto is named or referred to.

15. All notices to Sublessor shall be sent to Innovation Associates, c/o Arthur
    D. Little, Inc., 35 Acorn Park, Cambridge, MA 02140, Attn: Charles F.
    Kiefer, with a copy to Arthur D. Little, Inc., 20 Acorn Park, Cambridge, MA
    02140, Attn: Jose Bairos; all notices to Sublessee shall be sent to
    StorageNetworks, Inc., 100 Fifth Avenue, Waltham, MA 02451, Attn: Paul C.
    Flanagan, with a copy to Pamela Coravos, Esq., Hale and Dorr LLP, 60 State
    Street, Boston, MA 02109, or to such other address and attention as either
    party shall notify the other in writing.

                                       6
<PAGE>

16. Sublessee will have access to the Subleased Premises 24 hours per day, seven
    days a week via a card reader access system. Nightly janitorial service, on-
    site property management, elevator service and card key access are all
    included in the base rent. Sublessee shall have the non-exclusive right to
    use 63 parking spaces in the parking area serving the Subleased Premises at
    no extra charge. Signage for Sublessee, at Sublessee's sole cost and
    expense, shall be approved in advance by Sublessor and Master Lessor in
    accordance with the Master Lease.



                          [Intentionally left blank]


                                       7
<PAGE>

     1N WITNESS WHEREOF, the parties have executed this Sublease as of the date
first set forth above.

                                             Sublessor:

                                             INNOVATION ASSOCIATES, INC.

                                             By: /s/ John F. Burns
                                                ----------------------------
                                                John F. Burns
                                                Vice President



                                             Sublessee:

                                             STORAGENETWORKS, INC.

                                             By: /s/ Paul C. Flanagan
                                                ------------------------------
                                             Print Name: Paul C. Flanagan
                                                        ----------------------
                                             Title: CFO
                                                   ---------------------------


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