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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C.
20549_____________ Form
10-Q/A Amendment No. 1  _____________


|x |    | QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
      SECURITIES EXCHANGE ACT OF 1934 
|- | -- | ----------------------------------------------------------------------------------------------
|  |    |                                                                                               
|  |    | For the quarterly period ended September 30,
    2012                                         
|  |    |                                                                                               
|  | OR
|  |    |                                                                                               
|o |    | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
      SECURITIES EXCHANGE ACT OF 1934
|  |    |                                                                                               
|  |    | For the transition period from _______ to
    _______                                         

Commission File Number 1-13449
_____________

QUANTUM CORPORATION _____________

Incorporated Pursuant to the Laws of
the State of Delaware

IRS Employer Identification Number
94-2665054

1650 Technology Drive, Suite 800, San
Jose, California 95110

(408) 944-4000 _____________

Indicate by check mark whether the
registrant (1) has filed all reports required to be filed by Section 13 or 15(d)
of the Securities Exchange Act of 1934, during the preceding 12 months (or for
such shorter period that the registrant was required to file such reports), and
(2) has been subject to such filing requirements for the past 90 days.
Yes xNoo

Indicate by checkmark whether the
registrant has submitted electronically and posted on its corporate website, if
any, every Interactive Data File required to be submitted and posted pursuant to
Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12
months (or for such shorter period that the registrant was required to submit
and post such files). Yes x    Noo

Indicate by checkmark whether the
registrant is a large accelerated filer, an accelerated filer, a non-accelerated
filer, or a smaller reporting company. See the definition of large accelerated
filer, accelerated filer and smaller reporting company in Rule 12b-2 of the
Exchange Act.

|Large accelerated filero | Accelerated filer x | Non-accelerated filero | Smaller reporting company o
|------------------------ | ------------------- | ---------------------- | ---------------------------

Indicate by check mark whether the
registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).
Yes o    Nox

|As of
      the close of business on November 2, 2012, 240,765,014 shares of Quantum
      Corporations common stock were issued and outstanding.
|--------------------------------------------------------------------------------------------------------------------------------------------------

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EXPLANATORY NOTE

The purpose of this Amendment to
      Form 10-Q for the quarterly period ended September 30, 2012, originally
      filed with the Securities and Exchange Commission on November 9, 2012 (the
      "Form 10-Q"), is solely to file Exhibits 10.2, 10.3 and 10.4 which were
      inadvertently omitted.

No other changes have been made to
      the Form 10-Q. This Amendment speaks as of the original filing date of the
      Form 10-Q, does not reflect events that may have occurred subsequent to
      the original filing date and does not modify or update in any way
      disclosures made in the original Form 10-Q.

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SIGNATURE

Pursuant to the requirements of the
Securities Exchange Act of 1934, the registrant has duly caused this report to
be signed on its behalf by the undersigned thereunto duly authorized.

QUANTUM CORPORATION/s/
      LINDA M. BREARDLinda M. BreardChief Financial Officer(Principal Financial and Chief
      Accounting Officer)


Date: February 15, 2013

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EXHIBIT INDEX

| |         |  |                                                                                                                                                                                                                                                                  |  | Incorporated by
      Reference
| | ------- |  | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |  | -------------------------------
| | Exhibit |  |                                                                                                                                                                                                                                                                  |  |                                
| | Number  |  | Exhibit Description                                                                                                                                                                                                                                              |  | Form                           
| | 3.1     |  | Amended and Restated Certificate of Incorporation of
      Registrant.                                                                                                                                                                                           |  | 8-K                            
| | 3.2     |  | Amended and Restated By-laws of
      Registrant, as amended.                                                                                                                                                                                                    |  | 8-K                            
| | 3.3     |  | Certification of Amendment to the Bylaws of Quantum
      Corporation, as adopted on January 20, 2010.                                                                                                                                                           |  | 8-K                            
| | 4.1     |  | Stockholder Agreement, dated as of
      October 28, 2002, by and between Registrant and Private Capital
      Management.                                                                                                                                       |  | 10-Q                           
| | 4.2     |  | Indenture for 3.50% Convertible Senior Subordinated Notes due
      2015, between the Registrant and U.S. Bank National Association, as
      trustee, dated November 15, 2010, including the form of 3.50% Convertible
      Senior Subordinated Note due 2015. |  | 8-K                            
| | 4.3     |  | Indenture for 4.50% Convertible
      Senior Subordinated Notes due 2017, between the Registrant and U.S. Bank
      National Association, as trustee, dated October 31, 2012, including the
      form of 4.50% Convertible Senior Subordinated Note due 2017.  |  | 8-K                            
| | 10.1    |  | Quantum Corporation 2012 Long-Term Incentive Plan.*                                                                                                                                                                                                              |  | 8-K                            
| | 10.2    |  | Form of Restricted Stock Unit
      Agreement (U.S. Employees), under the Quantum Corporation 2012 Long-Term
      Incentive Plan.*                                                                                                                             |  |                                
| | 10.3    |  | Form of Restricted Stock Unit Agreement (Non-U.S. Employees),
      under the Quantum Corporation 2012 Long-Term Incentive Plan. *                                                                                                                              |  |                                
| | 10.4    |  | Form of Restricted Stock Unit
      Agreement (Directors), under the Quantum Corporation 2012 Long-Term
      Incentive Plan. *                                                                                                                                 |  |                                
| | 10.5    |  | Quantum Corporation Employee Stock Purchase Plan.*                                                                                                                                                                                                               |  | 8-K                            
| | 10.6    |  | Quantum Corporation Executive Officer
      Incentive Plan, Effective April 1, 2012.*                                                                                                                                                                            |  | 8-K                            
| | 31.1    |  | Certification of the Chief Executive Officer pursuant to
      Section 302(a) of the Sarbanes-Oxley Act of 2002.                                                                                                                                                |  |                                
| | 31.2    |  | Certification of the Chief Financial
      Officer pursuant to Section 302(a) of the Sarbanes-Oxley Act of 2002.
                                                                                                                                               |  |                                
| | 32.1    |  | Certification of Chief Executive Officer pursuant to 18
      U.S.C. section 1350, as adopted pursuant to section 906 of the
      Sarbanes-Oxley act of 2002.                                                                                                  |  |                                
| | 32.2    |  | Certification of Chief Financial
      Officer pursuant to 18 U.S.C. section 1350, as adopted pursuant to section
      906 of the Sarbanes-Oxley act of 2002.                                                                                                  |  |                                

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| |         |  |                                                                 |  | Incorporated by
      Reference
| | ------- |  | --------------------------------------------------------------- |  | -------------------------------
| | Exhibit |  |                                                                 |  |                                
| | Number  |  | Exhibit Description                                             |  | Form                           
| | 101.INS |  | XBRL Instance
      Document.                                 |  |                                
| | 101.SCH |  | XBRL Taxonomy Extension Schema
      Document.                |  |                                
| | 101.CAL |  | XBRL Taxonomy Extension
      Calculation Linkbase Document.  |  |                                
| | 101.DEF |  | XBRL Taxonomy Extension Definition Linkbase
      Document.   |  |                                
| | 101.LAB |  | XBRL Taxonomy Extension
      Label Linkbase Document.        |  |                                
| | 101.PRE |  | XBRL Taxonomy Extension Presentation
      Linkbase Document. |  |                                

|*  |  | Indicates management contract or compensatory plan or
      arrangement.                                                                                                                                                                                                                                                                                                                                    
|-- |  | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|  |  | Filed herewith.                                                                                                                                                                                                                                                                                                                                                                                             
|  |  | Furnished herewith.                                                                                                                                                                                                                                                                                                                                                                                         
| |  | XBRL (Extensible Business Reporting Language) information is
      furnished and not filed herewith, is not a part of a registration
      statement or prospectus for purposes of sections 11 or 12 of the
      Securities Act of 1933, is deemed not filed for purposes of section 18 of
      the Securities Exchange Act of 1934, and otherwise is not subject to
      liability under these sections.

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