Exhibit 99.2

                            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 quarterly report of Advanced Digital Information
Corporation (the "Company") on Form 10-Q for the period ended July 31, 2002 as
filed with the Securities and Exchange Commission on the date hereof (the "Form
10-Q"), I, Jon W. Gacek, Senior Vice President and Chief Financial Officer of
the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002, that:

      1. The Form 10-Q fully complies with the requirements of Section 13(a)
or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o(d)); and
      2. The information contained in the Form 10-Q fairly presents, in all
material respects, the financial condition and results of operations of the
Company.

Dated: September 16, 2002                /s/ JON W. GACEK
                                         ---------------------------------------
                                             Jon W. Gacek, Senior Vice President
                                             and Chief Financial Officer
                                             (Principal Financial and Accounting
                                             Officer)