Exhibit 10.4

THE SECURITES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AND HAVE BEEN ACQUIRED FOR INVESTMENT AND NOT WITH A
VEIW TO, OR IN CONNECTION WITH, THE SALE OR DISTRIBUTION THEREOF.  NO SUCH SALE
OR DISTRIBUTION MAY BE EFFECTED WITHOUT AN EFFECTIVE REGISTRATION STATEMENT
RELATED THERETO OR PURSUANT TO AN EXEMPTION FROM REGISTRATION.

PROMISSORY NOTE

$626,063.60

November 13, 2004

Palo Alto, California

            For value received, Symphony Service Corp., a Delaware corporation
(the “Company”), promises to pay to nStor Technologies, Inc. (the “Holder”), the
principal sum of Six Hundred Twenty-six Thousand Sixty-three Dollars and Sixty
Cents ($626,063.60).  Interest shall accrue from the date of this Note on the
unpaid principal at amount a rate equal to 5.0% per annum, compounded annually. 
This Note is one of six notes containing substantially identical terms and
conditions issued pursuant to that certain Stock Purchase Agreement, dated
September 15, 2004, by and between the Company, Palo Alto Acquisition
Corporation and the shareholders of Stonehouse Technologies, Inc. (the “Purchase
Agreement”).  Capitalized terms used but not defined herein shall have the
meanings set forth in the Purchase Agreement.  Such notes are referred to herein
as the “Notes”.  This Note is subject to the following terms and conditions.

             1.         Maturity.  This Note will automatically mature and be
due and payable on the 12-month anniversary of the Closing Date (the “Maturity
Date”).  Interest shall accrue on this Note but shall not be due and payable
until the Maturity Date.  Notwithstanding the foregoing, the entire unpaid
principal sum of this Note, together with accrued and unpaid interest thereon,
shall become immediately due and payable upon the insolvency of the Company, the
commission of any act of bankruptcy by the Company, the execution by the Company
of a general assignment for the benefit of creditors, the filing by or against
the Company of a petition in bankruptcy or any petition for relief under the
federal bankruptcy act or the continuation of such petition without dismissal
for a period of 90 days or more, or the appointment of a receiver or trustee to
take possession of the property or assets of the Company.

             2.         Payment; Prepayment.  All payments shall be made in
lawful money of the United States of America at such place as the Holder hereof
may from time to time designate in writing to the Company.  Payment shall be
credited first to the accrued interest then due and payable and the remainder
applied to principal.  Prepayment of this Note may be made at any time without
penalty.

             3.         Offset Rights to Principal Amount.  Notwithstanding
anything to the contrary contained herein, if the Final Working Capital as
determined in accordance with Section 1.3 of the Purchase Agreement is less than
$800,000, then the principal amount of this Note shall be automatically adjusted
in accordance with Section 1.3(b) of the Purchase Agreement.

             4.         Transfer; Successors and Assigns.  The terms and
conditions of this Note shall inure to the benefit of and be binding upon the
respective successors and assigns of the parties.  Notwithstanding the
foregoing, the Holder may not assign, pledge, or otherwise transfer this Note
without the prior written consent of the Company, except for transfers to
affiliates in accordance with the terms of the Purchase Agreement.  Subject to
the preceding sentence, this Note may be transferred only upon surrender of the
original Note for registration of transfer, duly endorsed, or accompanied by a
duly executed written instrument of transfer, in form satisfactory to the
Company.  Thereupon, a new note for the same principal amount and interest will
be issued to, and registered in the name of, the transferee.  Interest and
principal are payable only to the registered holder of this Note.

             5.         Governing Law.  This Note and all acts and transaction
pursuant hereto and the rights and obligation of the parties hereto shall be
governed, construed and interpreted in accordance with the laws of the State of
Delaware, without giving effect to principles of conflicts of law.

             6.         Amendments and Waivers.  Any term of this Note may be
amended only with the written consent of the Company and the Holder.  Any
amendment or waiver effected in accordance with this Section 6 shall be binding
upon the Company, the Holder and each transferee of any Note.

 
                                                                                  
COMPANY:

 
                                                                                  
SYMPHONY SERVICE CORP.

 
                                                                                  
By: /s/ Jeff Van Zanten
 
                                                                                  
Name: Jeff Van Zanten
 
                                                                                  
Title: Chief Financial Officer

 
                                                                                  
Address:
 
                                                                                              
4015 Miranda Avenue
 
                                                                                              
Palo Alto, California  94303

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