<Page>

                                                                    EXHIBIT 32.1


                            CERTIFICATION PURSUANT TO
                 18 U.S.C. Section 1350, as adopted pursuant to
                  Section 906 of the Sarbanes-Oxley Act of 2002

          In connection with the filing of the Quarterly Report on Form 10-Q for
the quarter ended September 30, 2004 (the "Report") by Iron Mountain
Incorporated (the "Company"), the undersigned, as the Chief Executive Officer of
the Company, hereby certifies pursuant to 18 U.S.C. Section 1350, as adopted
pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to my
knowledge:

          1. the Report fully complies with the requirements of Section 13(a) or
Section 15(d) of the Securities Exchange Act of 1934; and

          2. the information contained in the Report fairly presents, in all
material respects, the financial condition and results of operations of the
Company.


Date: November 9, 2004


                                                    /s/ C. Richard Reese
                                                    --------------------
                                                    C. Richard Reese
                                                    Chief Executive Officer