**Exhibit 21.1**

 
| **Subsidiary**                                         | ** ** | **Jurisdiction of    Organization** |
|--------------------------------------------------------|------------|-----------------------------------------------|
| U-Store-It,   L.P.                                     |       | Delaware                                      |
| Acquiport/Amsdell   III, LLC                           |       | Delaware                                      |
| Acquiport/Amsdell   IV, LLC                            |       | Delaware                                      |
| Acquiport/Amsdell   VI, LLC                            |       | Delaware                                      |
| Lantana   Property Owner’s Association, Inc. |       | Florida                                       |
| U-Store-It   Development LLC                           |       | Delaware                                      |
| U-Store-It   Mini Warehouse Co.                        |       | Ohio                                          |
| U-Store-It   Trust Luxembourg S.ar.l.                  |       | Luxembourg                                    |
| USI   II, LLC                                          |       | Delaware                                      |
| USI   Overseas Development Holding L.P.                |       | Delaware                                      |
| USI   Overseas Development LLC                         |       | Delaware                                      |
| USIFB   LP                                             |       | London                                        |
| USIFB   LLP                                            |       | London                                        |
| YASKY   LLC                                            |       | Delaware                                      |
| YSI   I LLC                                            |       | Delaware                                      |
| YSI   II LLC                                           |       | Delaware                                      |
| YSI   III LLC                                          |       | Delaware                                      |
| YSI   IV LLC                                           |       | Delaware                                      |
| YSI   IX GP LLC                                        |       | Delaware                                      |
| YSI   IX LP                                            |       | Delaware                                      |
| YSI   IX LP LLC                                        |       | Delaware                                      |
| YSI   Management LLC                                   |       | Delaware                                      |
| YSI   V LLC                                            |       | Delaware                                      |
| YSI   VI LLC                                           |       | Delaware                                      |
| YSI   VII GP LLC                                       |       | Delaware                                      |
| YSI   VII LP                                           |       | Delaware                                      |
| YSI   VII LP LLC                                       |       | Delaware                                      |
| YSI   VIII GP LLC                                      |       | Delaware                                      |
| YSI   VIII LP                                          |       | Delaware                                      |
| YSI   VIII LP LLC                                      |       | Delaware                                      |
| YSI   X GP LLC                                         |       | Delaware                                      |
| YSI   X LP                                             |       | Delaware                                      |
| YSI   X LP LLC                                         |       | Delaware                                      |
| YSI   XI GP LLC                                        |       | Delaware                                      |
| YSI   XI LP                                            |       | Delaware                                      |
| YSI   XI LP LLC                                        |       | Delaware                                      |
| YSI   XII GP LLC                                       |       | Delaware                                      |
| YSI   XII LP                                           |       | Delaware                                      |
| YSI   XII LP LLC                                       |       | Delaware                                      |
| YSI   XIII GP LLC                                      |       | Delaware                                      |
| YSI   XIII LP                                          |       | Delaware                                      |
| YSI   XIII LP LLC                                      |       | Delaware                                      |
| YSI   XIV GP LLC                                       |       | Delaware                                      |
| YSI   XIV LP                                           |       | Delaware                                      |
| YSI   XIV LP LLC                                       |       | Delaware                                      |
| YSI   XV LLC                                           |       | Delaware                                      |
| YSI   XVI LLC                                          |       | Delaware                                      |
| YSI   XVII GP LLC                                      |       | Delaware                                      |

 

----

 
| YSI   XVII LP                   |   | Delaware |
|---------------------------------|--------|----------|
| YSI   XVII LP LLC               |   | Delaware |
| YSI   XX GP LLC                 |   | Delaware |
| YSI   XX LP                     |   | Delaware |
| YSI   XX LP LLC                 |   | Delaware |
| YSI   XXI LLC                   |   | Delaware |
| YSI   XXIII LLC                 |   | Delaware |
| YSI   XXIV GP LLC               |   | Delaware |
| YSI   XXIV LP LLC               |   | Delaware |
| YSI   XXIX GP LLC               |   | Delaware |
| YSI   XXIX LP                   |   | Delaware |
| YSI   XXIX LP LLC               |   | Delaware |
| YSI   XXV GP LLC                |   | Delaware |
| YSI   XXV LP                    |   | Delaware |
| YSI   XXV LP LLC                |   | Delaware |
| YSI   XXVI GP LLC               |   | Delaware |
| YSI   XXVI LP                   |   | Delaware |
| YSI   XXVI LP LLC               |   | Delaware |
| YSI   XXVII GP LLC              |   | Delaware |
| YSI   XXVII LP                  |   | Delaware |
| YSI   XXVII LP LLC              |   | Delaware |
| YSI   XXVIII GP LLC             |   | Delaware |
| YSI   XXVIII LP                 |   | Delaware |
| YSI   XXVIII LP LLC             |   | Delaware |
| YSI   XXX LLC                   |   | Delaware |
| YSI   XXXI LLC                  |   | Delaware |
| YSI   XXXII LLC                 |   | Delaware |
| YSI   XXXIII LLC                |   | Delaware |
| YSI   XXXIIIA LLC               |   | Delaware |
| YSI   XXXIV LLC                 |   | Delaware |
| YSI   XXXV LLC                  |   | Delaware |
| YSI   XXXVII LLC                |   | Delaware |
| YSI   XXXVIII LLC               |   | Delaware |
| YSI   XXXIX LLC                 |   | Delaware |
| YSI   XXXX LLC                  |   | Delaware |
| YSI   XXXXI LLC                 |   | Delaware |
| YSI   XXXXII LLC                |   | Delaware |
| YSI   XXXXIII LLC               |   | Delaware |
| YSI   XXXXIV LLC                |   | Delaware |
| YSI   XXXXV LLC                 |   | Delaware |
| YSI   XXXXVI LLC                |   | Delaware |
| YSI   XXXXVII LLC               |   | Delaware |
| YSI   XXXXVIII LLC              |   | Delaware |
| YSI   XLIX LLC                  |   | Delaware |
| YSI   L LLC                     |   | Delaware |
| YSI   Venture LP LLC            |   | Delaware |
| YSI   Venture GP LLC            |   | Delaware |
| YSI-HART   Limited Partnership  |   | Delaware |
| YSI   HART TRS, Inc.       |   | Delaware |
| Storage   Asset Management, LLC |   | Delaware |
| Property   Guard, LLC           |   | Delaware |
| YSI   Burke Lake, LLC           |   | Delaware |

 

----