Exhibit 99.1

Joint Filing Agreement

Pursuant to and in accordance with the Securities Exchange Act of 1934, as amended, and the rules and regulations thereunder (the “Exchange Act”) the undersigned hereby agree to the joint filing on behalf of each of them of any filing required by such party under Section 13 of the Exchange Act or any rule or regulation thereunder (including any amendment, restatement, supplement, and/or exhibit thereto) with respect to securities of 21Vianet Group, Inc., a Cayman Islands company, and further agree to the filing, furnishing, and/or incorporation by reference of this Agreement as an exhibit thereto. Each of them is responsible for the timely filing of such filings and any amendments thereto, and for the completeness and accuracy of the information concerning such person contained therein; but none of them is responsible for the completeness or accuracy of the information concerning the other persons making the filing, unless such person knows or has reason to believe that such information is inaccurate. This Agreement shall remain in full force and effect until revoked by any party hereto in a signed writing provided to each other party hereto, and then only with respect to such revoking party. This Agreement may be executed in any number of counterparts all of which taken together shall constitute one and the same instrument.

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SIGNATURE

IN WITNESS WHEREOF, the undersigned hereby execute this Agreement as of July 2, 2020.

Vector Holdco Pte. Ltd.
By:	/s/ William Christian Greer Nicholson
Name:	William Christian Greer Nicholson
Title:	Director
BTO Vector Fund ESC (CYM) L.P.
By:	BTO Holdings (Cayman) - NQ Manager L.L.C., its general partner
By:	Blackstone Tactical Opportunities Management Associates (Cayman) - NQ L.P.,
	its managing member
By:	BTO GP - NQ L.L.C., a general partner
By:	/s/ Christopher J. James
Name:	Christopher J. James
Title:	Authorized Person
BTO Vector Fund FD (CYM) L.P.
By:	BTO Holdings (Cayman) - NQ Manager L.L.C., its general partner
By:	Blackstone Tactical Opportunities Management Associates (Cayman) - NQ L.P.,
	its managing member
By:	BTO GP - NQ L.L.C., a general partner
By:	/s/ Christopher J. James
Name:	Christopher J. James
Title:	Authorized Person
BTO Super Holding (NQ) Co. III Pte. Ltd.
By:	/s/ Kishore Moorjani
Name:	Kishore Moorjani
Title:	Director
Blackstone Tactical Opportunities SG II (Cayman) L.P.
By:	Blackstone Tactical Opportunities Management Associates (Cayman) - NQ L.P.,
	its general partner
By:	BTO GP - NQ L.L.C., a general partner
By:	/s/ Christopher J. James
Name:	Christopher J. James
Title:	Authorized Person

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BTO Holdings (Cayman) - NQ Manager L.L.C.
By:	Blackstone Tactical Opportunities Management Associates (Cayman) - NQ L.P., its managing member
By:	BTO GP - NQ L.L.C., a general partner
By:	/s/ Christopher J. James
Name:	Christopher J. James
Title:	Authorized Person
Blackstone Tactical Opportunities Management Associates (Cayman) - NQ L.P.
By:	BTO GP - NQ L.L.C., a general partner
By:	/s/ Christopher J. James
Name:	Christopher J. James
Title:	Authorized Person
BTO GP - NQ L.L.C.
By:	/s/ Christopher J. James
Name:	Christopher J. James
Title:	Authorized Person
Blackstone Tactical Opportunities LR Associates (Cayman) - NQ Ltd.
By: Blackstone Capital Holdings Director L.L.C., its director
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
Blackstone Holdings IV L.P.
By:	Blackstone Holdings IV GP L.P., its general partner
By:	Blackstone Holdings IV GP Management (Delaware) L.P., its general partner
By:	Blackstone Holdings IV GP Management L.L.C., its general partner
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
Blackstone Holdings IV GP L.P.
By:	Blackstone Holdings IV GP Management (Delaware) L.P., its general partner
By:	Blackstone Holdings IV GP Management L.L.C., its general partner
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
Blackstone Holdings IV GP Management (Delaware) L.P.
By:	Blackstone Holdings IV GP Management L.L.C., its general partner
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer

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Blackstone Holdings IV GP Management L.L.C.
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
The Blackstone Group Inc.
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
Blackstone Group Management L.L.C.
By:	/s/ John G. Finley
Name:	John G. Finley
Title:	Chief Legal Officer
Stephen A. Schwarzman
/s/ Stephen A. Schwarzman

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