X0303 4 2010-10-12 false 0001373671 Isilon Systems, Inc. ISLN 0001439716 Godwin Mary E. 3101 WESTERN AVENUE SEATTLE WA 98121 false true false false VP Operations Common Stock 2010-10-12 4 M false 2640 4.9 A 9240 D Common Stock 2010-10-12 4 M false 2040 2.57 A 11280 D Common Stock 2010-10-12 4 S false 4680 25.17 D 6600 D Stock Option (Right to Buy) 4.9 2010-10-12 4 M false 2640 0 D 2018-08-05 Common Stock 2640 174440 D Stock Option (Right to Buy) 2.57 2010-10-12 4 M false 2040 0 D 2019-05-15 Common Stock 2040 86840 D The option is exercisable at the rate of 25% of the shares on July 9, 2009 and 1/12th of the remaining shares on each quarterly anniversary thereafter, such that the option will be fully exercisable on July 9, 2012. The option is exercisable at the rate of 25% of the shares on May 1, 2010 and 1/12th of the remaining shares on each quarterly anniversary thereafter, such that the option will be fully exercisable on May 1, 2013. The sales reported by Ms. Godwin were effected pursuant to a Rule 10b5-1 trading plan adopted on May 26, 2010. Keenan M. Conder, Attorney-in-Fact 2010-10-14