<PAGE>   1
                                                                   EXHIBIT 10.18


                          [REGENT PACIFIC LETTERHEAD]

October 17, 2000


Mr. Richard L. Chapman, Director
Mr. John E. McNulty, Director
Mr. Karl C. Powell, Director
Auspex Systems, Inc.
2800 Scott Boulevard
Santa Clara, CA  95050


RE:     FIRST AMENDMENT TO RETAINER AGREEMENT BETWEEN REGENT PACIFIC MANAGEMENT
        CORPORATION AND AUSPEX SYSTEMS, INC.



This First Amendment to Retainer Agreement sets forth certain amendments to the
Retainer Agreement between Regent Pacific Management Corporation, a California
corporation ("Regent Pacific"), and Auspex Systems, Inc., a California
corporation, and its wholly-owned and controlled subsidiaries (collectively,
"Auspex") dated February 10, 2000, (the "Original Retainer Agreement"). Except
for the amendments expressly contained herein, the Original Retainer Agreement
shall remain in full force and effect.

1.   The paragraph regarding "Fees" of the Original Retainer Agreement is hereby
     amended in its entirety as follows:

        "FEES: We have agreed to provide the work product included in this
        agreement for a period of twenty-six (26) months, including twenty (20)
        months of non-cancelable services. The fees for these services shall be
        $75,000 per week payable in four (4) week increments, each to be paid in
        advance of each Regent Pacific standard four-week billing period. It is
        agreed and understood that the fees payable and the level of services
        provided will remain at their current levels. It is further agreed and
        understood that the payments of such cash fees are to be made
        immediately preceding the start of each four-week billing period, and
        that failure to pay such periodic payments when due shall constitute a
        breach of this agreement by Auspex. It is further understood that Regent
        Pacific's fees are to be paid in advance of the work to be performed,
        and that the initial payment is to be paid on or before the start of the
        engagement. It is further agreed that such cash payments are earned in
        full upon receipt by Regent Pacific, by virtue of our accepting this
        agreement and the responsibilities it entails, and are nonrefundable."


<PAGE>   2

Mr. Richard L. Chapman, Director
Mr. John E. McNulty, Director
Mr. Karl C. Powell, Director
October 17, 2000
Page 2



2.   The paragraph regarding "Term of agreement" of the Original Retainer
     Agreement is hereby amended in its entirety as follows:

        "TERM OF AGREEMENT: The term of this agreement shall be for twenty-six
        (26) months, including twenty (20) months of non-cancelable services,
        unless earlier terminated in accordance with the terms of this
        paragraph. Regent Pacific hereby commits the availability of its
        resources to Auspex under this agreement for the full twenty-six (26)
        month term of the engagement. Auspex may discharge Regent Pacific at any
        time after the non-cancelable period provided that Auspex delivers a
        60-day written notice of intent to cancel this agreement. Regent Pacific
        may withdraw from this assignment at any time with Auspex's consent or
        for good cause without Auspex's consent. Good cause includes Auspex's
        breach of this agreement (including Auspex's failure to pay any invoice
        within five working days of presentation), or any fact or circumstance
        that would render our continuing participation in the assignment
        unethical or unlawful."


3.   A new paragraph regarding "Stock Options" is hereby added to the Original
     Retainer Agreement. It reads in its entirety as follows:

        "STOCK OPTIONS: In addition to the cash fees payable to Regent Pacific
        under the terms of this agreement, it is agreed that Auspex will grant
        stock options to Gary J. Sbona and/or his designee from time to time,
        initially as an inducement for employment and subsequently as an
        incentive for agreeing to extend the term of this agreement. The initial
        stock option grant to Gary J. Sbona, dated February 14, 2000, was for
        two million four hundred thousand (2,400,000) shares of Auspex common
        stock. As part of this amendment, Auspex agrees that it will grant an
        option for an additional seven hundred fifty thousand (750,000) shares
        of Auspex common stock to Gary J. Sbona as of October 17, 2000 at the
        market closing price as of that date. The terms of this option grant,
        and of any subsequent option grants, shall be substantially similar to
        the February 14, 2000 option grant, including but not limited to a)
        vesting to commence immediately after the grant date, b) vesting to be
        monthly over a period of one year, or the remaining term of the
        Agreement, whichever is less, and c) the same "Change of Control" and
        the same Termination Period provisions as in the February 14, 2000
        option grant. Stock options in addition to those referenced in this
        amendment may be granted to Gary J. Sbona and/or his designee from time
        to time at the sole discretion of Auspex Board of Directors."

<PAGE>   3

Mr. Richard L. Chapman, Director
Mr. John E. McNulty, Director
Mr. Karl C. Powell, Director
October 17, 2000
Page 3



Very truly yours,

REGENT PACIFIC MANAGEMENT CORPORATION



By:  /s/  GARY J. SBONA
    -----------------------------------------
        Gary J. Sbona
        Chairman and Chief Executive Officer



THE FOREGOING IS HEREBY APPROVED AND AGREED TO:

Dated:  October 17, 2000

AUSPEX SYSTEMS, INC.

(Signifies full agreement with all terms and conditions)



By:  /s/  RICHARD L. CHAPMAN
    -----------------------------------------
        Mr. Richard L. Chapman, Director
        on Behalf of the Board of Directors



By:  /s/  JOHN E. McNULTY
    -----------------------------------------
        Mr. John E. McNulty, Director
        on Behalf of the Board of Directors



By:  /s/  KARL C. POWELL
    -----------------------------------------
        Mr. Karl C. Powell, Director
        on Behalf of the Board of Directors