A table of organizations having largest Hadoop clusters.

1. List of Organizations with largest Hadoop Clusters
Company Name Number of Nodes Company Name Number of Nodes
Yahoo! 42,000 Adobe 30
LinkedIn 4100 Gruter. Corp. 30
Facebook 1400 IIIT 30
NetSeer 1050 Infochimps 30
EBay 532 Rackspace 30
CRS4 400 University of Glasgow 30
Powerset / Microsoft 400 Forward3D 24
Adknowledge 200 Bixo Labs 20
Neptune 200 Brockmann Consult GmbH 20
AOL 150 Datagraph 20
Inmobi 150 Kalooga 20
FOX Audience Network 140 Media 6 Degrees 20
Specific Media 138 Mercadolibre.com 20
Search Wikia 125 GBIF 18
eCircle 120 MicroCode 18
Spotify 120 MyLife 18
A9.com 100 SLC Security Services LLC 18
ARA.COM.TR 100
ETH Zurich Systems
Group 16
Cornell 100 RightNow Technologies 16
Last.fm 100 Taragana 16
Tynt 94 University of Twente 16
Deepdyve 80 Alibaba 15
Rapleaf 80 Caree.rs 15
Rakuten 69 Charleston 15
Telenav 60 Cooliris 15
Contextweb 50 Beebler 14
Hadoop Korean User
Group 50 Socialmedia.com 14
Openstat 50 Hulu 13
Portabilité 50 adyard 12
Recruit 50 Accela Communications 10
WorldLingo 44 Brilig 10
Rovi Corporation 40 Iterend 10
Benipal Technologies 35 Clic 10
Redpoll 35 PSG Tech 10
Source: http://www.hadoopwizard.com/which-big-data-company-has-the-worlds-biggest-hadoop-cluster