Exhibit 99.2

JOINDER AGREEMENT

This JOINDER AGREEMENT (the “Joinder”) is dated as of May 14, 2013 by and between Starboard Value and Opportunity Master Fund Ltd, a Cayman Islands exempted company, Starboard Value and Opportunity S LLC, a Delaware limited liability company, Starboard Value and Opportunity C LP, a Delaware limited partnership, Starboard Value LP, a Delaware limited partnership, Starboard Value GP LLC, a Delaware limited liability company, Starboard Principal Co LP, a Delaware limited partnership, Starboard Principal Co GP LLC, a Delaware limited liability company, Jeffrey C. Smith, Mark R. Mitchell, and Peter A. Feld (collectively, the “Existing Members”) and Starboard Value R LP, a Delaware limited partnership, and Starboard Value R GP LLC, a Delaware limited liability company (the “New Members”).

WHEREAS, the Existing Members are parties to that certain Joint Filing Agreement dated as of November 1, 2012 (the “Agreement”) and that certain Joinder Agreement dated as of March 15, 2013, pursuant to which the Existing Members agreed to the joint filing on behalf of each of them of a Statement on Schedule 13D (including additional amendments thereto) with respect to the shares of Common Stock, $0.01 par value, of Quantum Corporation, a Delaware corporation; and

WHEREAS, the New Members desire to join the group formed by the Existing Members.

NOW, THEREFORE, in consideration of the premises and of the mutual covenants and agreements of the parties herein contained, the parties hereby agree as follows:

1.         Effective immediately, each of the New Members is joined as a party to the Agreement.

2.         Each of the New Members agrees to be bound by the terms of the Agreement, the terms of which are incorporated herein and made a part hereof.

3.         This Joinder may be executed in counterparts, each of which shall be deemed an original and all of which, taken together, shall constitute but one and the same instrument, which may be sufficiently evidenced by one counterpart.

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IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed as of the day and year first above written.

STARBOARD VALUE AND OPPORTUNITY MASTER FUND LTD By: Starboard Value LP,        its investment manager   STARBOARD VALUE AND OPPORTUNITY S LLC By: Starboard Value LP,        its manager   STARBOARD VALUE AND OPPORTUNITY C LP By: Starboard Value R LP,        its general partner   STARBOARD VALUE R LP By: Starboard Value R GP LLC,        its general partner   STARBOARD VALUE LP By: Starboard Value GP LLC,        its general partner   STARBOARD VALUE GP LLC By: Starboard Principal Co LP,        its member     STARBOARD PRINCIPAL CO LP By: Starboard Principal Co GP LLC,        its general partner   STARBOARD PRINCIPAL CO GP LLC   STARBOARD VALUE R GP LLC

By:	/s/ Jeffrey C. Smith
	Name:	Jeffrey C. Smith
	Title:	Authorized Signatory

/s/ Jeffrey C. Smith

JEFFREY C. SMITH

Individually and as attorney-in-fact for Mark R. Mitchell and Peter A. Feld