X0202 3 2006-12-14 0 0001373671 Isilon Systems, Inc. ISLN 0001112239 SEQUOIA CAPITAL X 3000 SAND HILL ROAD BUILDING 4-180 MENLO PARK CA 94025 0 0 1 0 0001119873 SEQUOIA TECHNOLOGY PARTNERS X LP 3000 SAND HILL ROAD BUILDING 4-180 MENLO PARK CA 94025 0 0 1 0 0001127112 SEQUOIA CAPITAL X PRINCIPALS FUND LLC 3000 SAND HILL ROAD BUILDING 4-180 MENLO PARK CA 94025 0 0 1 0 0001206787 SC X MANAGEMENT LLC 3000 SAND HILL ROAD BUILDING 4-180 MENLO PARK CA 94025 0 0 1 0 0001195580 LEONE DOUGLAS M 3000 SAND HILL ROAD BUILDING 4-180 MENLO PARK CA 94025 0 0 1 0 0001201045 MORITZ MICHAEL J 3000 SAND HILL ROAD BUILDING 4-180 MENLO PARK CA 94025 0 0 1 0 0001201421 GOGUEN MICHAEL L 3000 SAND HILL ROAD BUILDING 4-180 MENLO PARK CA 94025 0 0 1 0 Series B Preferred Stock Common Stock 6853069 I See footnote Series C Preferred Stock Common Stock 2485829 I See footnote Series D Preferred Stock Common Stock 1965056 I See footnote Series E Preferred Stock Common Stock 347649 I See footnote These shares of Preferred Stock will automatically convert into shares of Common Stock upon the closing of the Issuer's initial public offering on a 1-for-1 basis. Not applicable. Reflects a 1-for-2.4 reverse stock split effected immediately prior to the filing date. These shares of Preferred Stock will automatically convert into shares of Common Stock upon the closing of the Issuer's initial public offering on a 1-for-1 basis. Includes 5,400,219 shares held by Sequoia Capital X, 652,412 shares held by Sequoia Capital X Principals Fund and 800,438 shares held by Sequoia Technology Partners X. Greg McAdoo (who is a director of the Issuer and files separate Section 16(a) reports) is a non-managing member of various entities affiliated with Sequoia Capital. Douglas M. Leone, Michael J. Moritz and Michael L. Goguen are managing members of SC X Management, L.L.C., the general partner of Sequoia Capital X and Sequoia Technology Partners X, and the managing member of Sequoia Capital X Principals Fund. Each of the Filing Persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein. Includes 2,015,759 shares held by Sequoia Capital X, 179,725 shares held by Sequoia Capital X Principals Fund and 290,345 shares held by Sequoia Technology Partners X. Each of the Filing Persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein. Includes 1,593,465 shares held by Sequoia Capital X, 142,073 shares held by Sequoia Capital X Principals Fund and 229,518 shares held by Sequoia Technology Partners X. Each of the Filing Persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein. Includes 281,909 shares held by Sequoia Capital X, 25,135 shares held by Sequoia Capital X Principals Fund and 40,605 shares held by Sequoia Technology Partners X. Each of the Filing Persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein. /s/ Douglas M. Leone Authorized signer 2006-12-12 Douglas M. Leone 2006-12-12 Douglas M. Leone 2006-12-12 Douglas M. Leone 2006-12-12 Douglas M. Leone 2006-12-12 Michael J. Moritz 2006-12-12 Michael L. Goguen 2006-12-12