EXHIBIT A JOINT FILING AGREEMENT

EXHIBIT A

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the undersigned agree to the joint filing on behalf of each of them of a statement on Schedule 13G (including amendments thereto) with respect to the Common Stock of Compellent Technologies, Inc. and further agree that this agreement be included as an exhibit to such filing. Each party to the agreement expressly authorizes each other party to file on its behalf any and all amendments to such statement. Each party to this agreement agrees that this joint filing agreement may be signed in counterparts.

In evidence whereof, the undersigned have caused this Agreement to be executed on their behalf this 23^rd day of February, 2011.

CRESCENDO IV, L.P.						CRESCENDO IV AG & CO. BETEILIGUNGS KG
By:		Crescendo Ventures IV, LLC				By:		Crescendo German Investments IV, LLC
		its general partner						its general partner
By:		/s/ R. Xxxxx Xxxxxx				By:		/s/ R. Xxxxx Xxxxxx
		R. Xxxxx Xxxxxx						R. Xxxxx Xxxxxx
		Managing General Partner						Managing General Partner
CRESCENDO IV ENTREPRENEURS FUND, L.P.						CRESCENDO IV ENTREPRENEURS FUND A, L.P.
By:		Crescendo Ventures IV, LLC				By:		Crescendo Ventures IV, LLC
		its general partner						its general partner
By:		/s/ R. Xxxxx Xxxxxx				By:		/s/ R. Xxxxx Xxxxxx
		R. Xxxxx Xxxxxx						R. Xxxxx Xxxxxx
		Managing General Partner						Managing General Partner
CRESCENDO VENTURES IV, LLC						CRESCENDO GERMAN INVESTMENTS IV, LLC
By:		/s/ R. Xxxxx Xxxxxx				By:		/s/ R. Xxxxx Xxxxxx
		R. Xxxxx Xxxxxx						R. Xxxxx Xxxxxx
		Managing General Partner						Managing General Partner
/s/ R. Xxxxx Xxxxxx
R. Xxxxx Xxxxxx

Page 12 of 12 Pages