Document:

<PAGE>
                                                                  EXHIBIT 10.4

                           AMENDMENT NO. 4 TO GUARANTY

     AMENDMENT NO. 4 TO UNCONDITIONAL GUARANTY dated as of March 20, 2001
between IRON MOUNTAIN INCORPORATED, a Pennsylvania corporation (Guarantor),
formerly known as Pierce Leahy Corp. as survivor by merger with Iron Mountain
Incorporated, a Delaware corporation (IM Delaware), and IRON MOUNTAIN STATUTORY
TRUST - 1999, a Connecticut statutory trust (Owner), and consented to by each of
the Lenders and Agent Bank listed on the signature pages hereto.

     Guarantor and Owner are parties to a certain Unconditional Guaranty dated
as of July 1, 1999, as amended by Amendment No. 1 and Consent to Guaranty dated
as of October 22, 1999, Amendment No. 2 and Consent to Guaranty dated as of
January 31, 2000 and Amendment No. 3 and Consent to Guaranty dated as of August
16, 2000 (the Guaranty) pursuant to which Guarantor has guaranteed to Owner and
the Indemnified Parties the Guaranteed Obligations, including, without
limitation, certain obligations of Iron Mountain Records Management, Inc.
(Lessee/Agent) under (i) a Lease Agreement from Owner to Lessee/Agent dated as
of July 1, 1999 (the Lease), and (ii) an Agency Agreement between Lessee/Agent
and Owner dated as of July 1, 1999 (the Agency Agreement). Each of the Lease and
the Agency Agreement have been assigned to the Agent Bank pursuant to an
Assignment of Lease and Agency Agreement from Owner to Agent Bank and consented
to by Lessee/Agent dated as of July 1, 1999.

     Guarantor has requested that the Section 10(a)(iv)(ii) of the Guaranty be
amended as set forth below. Accordingly, the parties hereto agree as follows:

     SECTION 1. DEFINITIONS. Except as otherwise defined in this Agreement,
terms defined in the Guaranty are used herein as defined therein.

     SECTION 2. AMENDMENTS. Subject to the terms and conditions contained
herein, the Guaranty is hereby amended as follows:

          (a)   SUBORDINATED INDEBTEDNESS. Section 10(a)(iv)(ii) of the Guaranty
is hereby deleted in its entirety and replaced with the following:

               "(ii) any other purchase, redemption or retirement of
          Subordinated Indebtedness, so long as (i) no Default has occurred and
          is continuing and (ii) either (A) unless such other purchase,
          redemption or retirement is in connection with a refinancing of such
          Subordinated Indebtedness with the proceeds of, or in connection with
          an exchange of such Subordinated Indebtedness for a new series of,
          Senior Subordinated Debt issued within 60 days of the substantial
          completion of such purchase, redemption or retirement, or (B) after
          giving effect to such purchase, redemption or retirement, the ratio of
          Senior Debt on the last day of the most recently completed fiscal
          quarter of the Guarantor to EBITDA for the four quarters then ended on
          a PRO FORMA basis, after giving effect to such purchase, redemption or
          retirement and any Stock Repurchase consummated on or prior to

<PAGE>

          the date hereof, and to any borrowings to finance the same, as at the
          last day of the latest fiscal quarter is less than or equal to 1.5 to
          1."

     SECTION 3. CONDITIONS OF EFFECTIVENESS. This Agreement shall become
effective as of the date hereof when, and only when, the Owner, the Lenders and
the Agent Bank shall have received a counterpart of this Agreement duly executed
by the parties hereto.

     SECTION 4. REPRESENTATIONS AND WARRANTIES. As of the date hereof, Guarantor
hereby represents and warrants to Owner, Agent Bank, the Lenders and their
respective counsel that:

          (a)   the representations and warranties made by Guarantor in each
Operative Document to which it is a party are correct on and as of the date
hereof, as though made on and as of such date (or, if any such representation or
warranty is expressly stated to have been made as of a specific date, as of such
specific date); and

          (b)   no event has occurred and is continuing under any Operative
Document that constitutes a Default or an Event of Default.

     SECTION 5. MISCELLANEOUS. Except as herein provided, the Guaranty and each
of the other Operative Documents shall remain unchanged and in full force and
effect. Upon the effectiveness of this Agreement, on and after the date hereof,
each reference in any Operative Document to the Guaranty shall mean and be a
reference to the Guaranty as amended hereby. This Agreement may be executed in
any number of counterparts, all of which taken together shall constitute one and
the same instrument and any of the parties hereto may execute this Agreement by
signing any such counterpart. This Agreement shall be governed by, and construed
in accordance with, the law of the Commonwealth of Massachusetts.

                  [Remainder of Page Intentionally Left Blank]

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     IN WITNESS WHEREOF, the parties hereunto have caused this Agreement to be
executed by their respective officers thereunto duly authorized, as of the date
first above written.

                                              GUARANTOR:

                                              IRON MOUNTAIN INCORPORATED

                                              By: /s/ J.P. Lawrence
                                                 ------------------------------
                                              Name: J.P.Lawrence
                                              Title: VP & Treasurer

                                              LENDERS:

                                              WACHOVIA CAPITAL INVESTMENTS,
                                              INC., as Agent Bank and as a
                                              Lender

                                              By: /s/ Charles J. O'Connor, Jr.
                                                 ------------------------------
                                              Name:  Charles J. O'Connor, Jr.
                                              Title: Senior Vice President

                           [GUARANTY AMENDMENT NO.4]

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                                              PNC COMMERCIAL, LLC

                                              By: /s/ John McEnery
                                                 ------------------------------
                                              Name: John McEnery
                                              Title: Vice President

                                              CITIZENS BANK OF MASSACHUSETTS AS
                                              SUCCESSOR-IN-INTEREST TO
                                              USTRUST

                                              By: /s/ Edward C. Thaute
                                                 ------------------------------
                                              Name:  Edward C. Thaute
                                              Title: Vice President

                                              NATIONAL CITY BANK

                                              By: /s/ Melissa Lindsy
                                                 ------------------------------
                                              Name:  Melissa Lindsy
                                              Title: Vice President

                                              DIAMOND LEASE (U.S.A.) INC.

                                              By: /s/ Jeffrey H. Fishman
                                                 ------------------------------
                                              Name:  JEFFREY H. FISHMAN
                                              Title: VP, Credit Administration

                                              BANK OF NEW YORK

                                              By: /s/ Kenneth P. Sneider, Jr.
                                                 ------------------------------
                                              Name:  Kenneth P. Sneider, Jr.
                                              Title: Vice President

                           [GUARANTY AMENDMENT NO.4]

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                                              OWNER:

                                              IRON MOUNTAIN STATUTORY TRUST -
                                              1999

                                              By: First Union National Bank,
                                                  not in its individual
                                                  capacity, but solely as
                                                  trustee

                                              By: /s/ W. Jeffrey Kramer
                                                 ------------------------------
                                              Name:  W. JEFFREY KRAMER
                                              Title: VICE PRESIDENT

                           [GUARANTY AMENDMENT NO.4]<PAGE>

                                                               EXHIBIT 10.5

                     AMENDMENT NO. 5 AND CONSENT TO GUARANTY

     AMENDMENT NO. 5 AND CONSENT TO UNCONDITIONAL GUARANTY dated as of
March 15, 2002 between IRON MOUNTAIN INCORPORATED, a Pennsylvania corporation
("GUARANTOR") and IRON MOUNTAIN STATUTORY TRUST - 1999, a Connecticut
statutory trust ("OWNER"), and consented to by each of the Lenders and Agent
Bank listed on the signature pages hereto.

     Guarantor and Owner are parties to a certain Unconditional Guaranty dated
as of July 1, 1999 as amended by Amendment No. 1 and Consent to Guaranty dated
as of October 22, 1999, Amendment No. 2 and Consent to Guaranty dated as of
January 31, 2000, Amendment No. 3 and Consent to Guaranty dated as of August 16,
2000 and Amendment No. 4 and Consent to Guaranty dated as of March 20, 2001
(collectively, the "GUARANTY") pursuant to which the Guarantor guarantees to
Owner and the Indemnified Parties the Guaranteed Obligations, including, without
limitation, certain obligations of Iron Mountain Information Management, Inc.
(f/k/a "Iron Mountain Records Management, Inc.") ("LESSEE/AGENT") under (i) a
Lease Agreement from Owner to Lessee/Agent dated as of July 1, 1999 (as amended
or supplemented from time to time, the "LEASE"), and (ii) an Agency Agreement
between Lessee/Agent and Owner dated as of July 1, 1999 (the "AGENCY
AGREEMENT"). Each of the Lease and the Agency Agreement have been assigned to
the Agent Bank pursuant to an Assignment of Lease and Agency Agreement from
Owner to Agent Bank and consented to by Lessee/Agent dated as of July 1, 1999.
Guarantor has requested that Owner, Agent Bank and the Lenders amend the
Guaranty with respect to certain covenants and related definitions; and
Guarantor has requested that the Lenders and Agent Bank consent to such changes.
Accordingly, the parties hereto agree as follows:

     Section 1. DEFINITIONS. Except as otherwise defined in this Agreement,
terms defined in the Guaranty are used herein as defined therein.

     Section 2. AMENDMENTS. Subject to the terms and conditions contained
herein, the Guaranty is hereby  amended as follows:

     A. SECTION 9. Section 9 of the Guaranty is hereby by amended by adding a
new last paragraph thereto to read as follows:

     "Any financial statement or other document required to be delivered
pursuant to this Section 9 shall be deemed to have been delivered on the date on
which the Guarantor posts such financial statement or such document on the
Intralinks website on the Internet at www.intralinks.com; provided that the
Guarantor shall give notice of any such posting (together with access
instructions therefor) to the Agent Bank (and the Agent Bank shall then give
notice of any such posting with such access instructions to the Lenders).
Notwithstanding the foregoing, the Guarantor shall deliver paper copies of any
financial statement or other document referred to in this Section 9 to the Agent
Bank if the Agent Bank or any Lender requests the

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Guarantor to deliver such paper copies until written notice to cease delivering
such paper copies is given by the Agent Bank."

     B. SECTION 10(a)(v). Section 10(a)(v) (LIENS) of the Guaranty is hereby
amended by deleting in clause (iv)(B) thereof the amount "$3,000,000" and
replacing it with the amount "$10,000,000".

     C. SECTION 10(c). The defined term "Credit Agreement" set forth in Section
10(c) of the Guaranty is hereby amended and restated as follows:

     "CREDIT AGREEMENT shall mean the Fifth Amended and Restated Credit
Agreement dated as of March 15, 2002 among Guarantor and the other parties
thereto as amended, amended and restated, modified, extended, refinanced or
supplemented from time to time, except to the extent that the Operative
Documents refer to it as in effect on the date hereof."

     D. PERMITTED TRANSACTIONS. Section 10(d)(x) of the Guaranty is hereby
amended by adding the following after the last sentence thereof:

     "Nothing in this Guaranty or any Operative Document shall, or shall be
deemed to, prohibit or restrict the merger of the Guarantor with or into another
corporation for the sole purpose of changing the Guarantor's domicile from
Pennsylvania to Delaware, so long as the surviving corporation of such merger,
if such surviving corporation is not the Guarantor, shall expressly assume in
writing the obligations of the Guarantor under this Agreement and the other
Operative Documents to which Guarantor is a party and expressly agree in writing
to be bound by all other provisions applicable to the Guarantor under this
Guaranty and such Operative Documents in a manner reasonably satisfactory to the
Agent Bank."

     Section 3. CONDITIONS OF EFFECTIVENESS. This Agreement shall become
effective as of the date hereof when, and only when, the Owner, the Lenders and
the Agent Bank shall have received a counterpart of this Agreement duly executed
by the parties hereto.

     Section 4. REPRESENTATIONS AND WARRANTIES. As of the date hereof, Guarantor
hereby represents and warrants to Owner, Agent Bank, the Lenders and their
respective counsel that:

     A. the representations and warranties made by Guarantor in each Operative
Document to which it is a party and the Guarantor Certificate dated and
delivered to the Lenders as of February 1, 2000 are true and correct in all
material respects on and as of the date hereof, as though made on and as of such
date (or, if any such representation or warranty is expressly stated to have
been made as of a specific date, as of such specific date); and

     B. no event has occurred and is continuing under any Operative Document
that constitutes a Default or an Event of Default.

     Section 5. MISCELLANEOUS. Except as herein provided, the Guaranty and each
of the other Operative Documents shall remain unchanged and in full force and
effect. Upon the effectiveness of this Agreement, on and after the date hereof,
each reference in any Operative Document to the Guaranty shall mean and be a
reference to the Guaranty as amended hereby. This Agreement may be executed in
any number of counterparts, all of which taken together

                                       -2-
<PAGE>

shall constitute one and the same instrument and any of the parties hereto may
execute this Agreement by signing any such counterpart. This Agreement shall be
governed by, and construed in accordance with, the law of the Commonwealth of
Massachusetts.

                                       -3-
<PAGE>

     IN WITNESS WHEREOF, the parties hereunto have caused this Agreement to be
executed by their respective officers thereunto duly authorized, as of the date
first above written.

                                              GUARANTOR:

                                              IRON MOUNTAIN INCORPORATED

                                              By: /s/ J.P. Lawrence
                                                 ------------------------------
                                              Name: J.P. Lawrence
                                              Title: Vice President and
                                                     Treasurer

                                              OWNER:

                                              IRON MOUNTAIN STATUTORY TRUST --
                                              1999

                                              By: First Union National Bank, not
                                                  in its individual capacity,
                                                  but solely as trustee

                                              By: /s/ Timothy A. Donmoyer
                                                 ------------------------------
                                              Name:  /s/ Timothy A. Donmoyer
                                              Title: Vice President

                                              Consented to by:

                                              LENDERS:

                                              WACHOVIA CAPITAL INVESTMENTS,
                                              INC., as Agent Bank and
                                              as a Lender

                                              By: /s/ J. Andrew Phelps
                                                 ------------------------------
                                              Name: J. Andrew Phelps
                                              Title: Vice President

                           [GUARANTY AMENDMENT NO. 5]

<PAGE>

                                              PNC COMMERCIAL LLC

                                              By: /s/ John F. McEnery
                                                 ------------------------------
                                              Name: John F. McEnery
                                              Title: Vice President

                                              CITIZENS BANK OF MASSACHUSETTS
                                              f/k/a USTRUST

                                              By: /s/ Edward C. Thaute
                                                 ------------------------------
                                              Name: Edward C. Thaute
                                              Title: Vice President

                                              NATIONAL CITY BANK

                                              By: /s/ Tara M. Handforth
                                                 ------------------------------
                                              Name: Tara M. Handforth
                                              Title: Assistant Vice President

                                              DIAMOND LEASE (U.S.A.) INC.

                                              By: /s/ Jeffrey H. Fishman
                                                 ------------------------------
                                              Name: Jeffrey H. Fishman
                                              Title: Vice President, Credit
                                                     Administration

                                              BANK OF NEW YORK

                                              By: /s/ Kenneth Sneider
                                                 ------------------------------
                                              Name: Kenneth Sneider
                                              Title: Vice President

                            [GUARANTY AMENDMENT NO. 5]

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