SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Schedule 13G
(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULES 13d-1 (b), (c) AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO 13d-2 (b)

(Amendment No. 1)

ISILON SYSTEMS, INC.

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

46432L104

(CUSIP Number)

12/31/10

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

(Continued on following pages)

Page 1 of 9 Pages

CUSIP NO. 46432L104 13 G Page 2 of 9 Pages


1	NAME OF REPORTING PERSON SEQUOIA CAPITAL X (“SC X”) I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) 77-0535705
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0
		6	SHARED VOTING POWER 0
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 0
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 0
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.0%
12	TYPE OF REPORTING PERSON PN

CUSIP NO. 46432L104 13 G Page 3 of 9 Pages


1	NAME OF REPORTING PERSON SEQUOIA TECHNOLOGY PARTNERS X (“STP X”) I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) 77-0537311
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0
		6	SHARED VOTING POWER 0
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 0
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 0
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.0%
12	TYPE OF REPORTING PERSON PN

CUSIP NO. 46432L104 13 G Page 4 of 9 Pages


1	NAME OF REPORTING PERSON SEQUOIA CAPITAL X PRINCIPALS FUND, L.L.C. (“SC X PF”) I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) 77-0537312
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0
		6	SHARED VOTING POWER 0
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 0
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 0
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.0%
12	TYPE OF REPORTING PERSON OO

CUSIP NO. 46432L104 13 G Page 5 of 9 Pages


1	NAME OF REPORTING PERSON SC X MANAGEMENT, LLC (“SC X LLC”) I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) 77-0535710
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) o (b) x
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER 0
		6	SHARED VOTING POWER 0
		7	SOLE DISPOSITIVE POWER 0
		8	SHARED DISPOSITIVE POWER 0
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 0
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 0.0%
12	TYPE OF REPORTING PERSON OO

CUSIP NO. 46432L104 13 G Page 6 of 9 Pages

ITEM 1.

(a)

Name of Issuer:

Isilon Systems, Inc.

(b)

Address of Issuer’s Principal Executive Offices:

3101 Western Avenue

Seattle, Washington 98121

ITEM 2.

(a)

Name of Persons Filing:

Sequoia Capital X

Sequoia Technology Partners X

Sequoia Capital X Principals Fund, L.L.C.

SC X Management, LLC

SC X LLC is the General Partner of SC X and STP X, and the Managing Member of SC X PF.

(b)

Address of Principal Business Office or, if none, Residence:

3000 Sand Hill Road, 4-250

Menlo Park, CA 94025

(c)

Citizenship:

SC X LLC, SC X, STP X, SC X PF: Delaware

(d)

Title of Class of Securities:

Common Stock

(e)

CUSIP Number:

46432L104

ITEM 3. If this statement is filed pursuant to Rules 13d-1(b) or 13d-2(b) or (c), check whether the person filing is a:

NOT APPLICABLE

ITEM 4. Ownership

SEE ROWS 5 THROUGH 11 OF COVER PAGES

CUSIP NO. 46432L104 13 G Page 7 of 9 Pages

ITEM 5.

OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following. x

ITEM 6.

OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON

NOT APPLICABLE

ITEM 7.

IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY OR CONTROL PERSON

NOT APPLICABLE

ITEM 8.

IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP

NOT APPLICABLE

ITEM 9.

NOTICE OF DISSOLUTION OF GROUP

NOT APPLICABLE

ITEM 10.

CERTIFICATION

NOT APPLICABLE

CUSIP NO. 46432L104 13 G Page 8 of 9 Pages

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: February 9, 2011

Sequoia Capital X, a Delaware Limited Partnership

Sequoia Technology Partners X, a Delaware Limited Partnership

By: SC X Management, LLC,

their General Partner

By: /s/ Douglas Leone

Douglas Leone, Managing Member

Sequoia Capital X Principals Fund L.L.C.

By: SC X Management, LLC,

Its Managing Member

By: /s/ Douglas Leone

Douglas Leone, Managing Member

SC X Management, LLC

By: /s/ Douglas Leone

Douglas Leone, Managing Member

CUSIP NO. 46432L104 13 G Page 9 of 9 Pages

EXHIBIT 1

AGREEMENT AS TO JOINT FILING OF SCHEDULE 13G

The undersigned hereby agree that the Schedule 13G relating to the common shares of Isilon Systems, Inc., and any further amendments thereto, to which this Agreement as to Joint Filing of Schedule 13G is attached as an exhibit is filed on behalf of each of them pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended.

Date: February 9, 2011

Sequoia Capital X, a Delaware Limited Partnership

Sequoia Technology Partners X, a Delaware Limited Partnership

By: SC X Management, LLC,

their General Partner

By: /s/ Douglas Leone

Douglas Leone, Managing Member

Sequoia Capital X Principals Fund L.L.C.

By: SC X Management, LLC,

Its Managing Member

By: /s/ Douglas Leone

Douglas Leone, Managing Member

SC X Management, LLC

By: /s/ Douglas Leone

Douglas Leone, Managing Member

Isilon Systems, Inc. SC 13G/A