The "ClueWeb09 Gap Data Set " data set file info:

Archive file MD5:
6457a2e7387721296425cda359f09664  MindTheGap.7z.001
ef6dc0078a6565a7336769ac4a9d9cd9  MindTheGap.7z.002
fdc501db8147f15609e5cced77654e60  MindTheGap.7z.003
6905c633f480abc0bf91fd43d45f982a  MindTheGap.7z.004
b2e330ee00b993dd058c70e18a39a699  MindTheGap.7z.005
9e933ad60f0af5e6ca1eced5ad2ae3ad  MindTheGap.7z.006
6c2164e7b093628af6d6a59bc9afc339  MindTheGap.7z.007
7c7ee2d970b5941e418d24855e17f5c8  MindTheGap.7z.008
f319284aa52e0b3721d292f2c346381f  MindTheGap.7z.009
8901d829004681802c2fc1338cf69f42  MindTheGap.7z.010
e388f23b1bfe8487541234267c1254f1  MindTheGap.7z.011
e0a09c2c4e5b07a958ed7c4b9af55453  MindTheGap.7z.012
77274dec1809157b6a4f0633599b58c5  MindTheGap.7z.013
97978fd30ccc3454060c20e4c3e532d2  MindTheGap.7z.014
457ffb6429f17da925048a64dd54bdf1  MindTheGap.7z.015
a4f98332c5ed99586b3cd971bed73ebe  MindTheGap.7z.016


dict 4233a6b972fe32b08d977169fa9b0aca
inv  1edeeb9e78d75e3d57e6747ffcf5dc2a 

The "flat" file produced by the toflat utility:
Size: 54897549640 bytes
MD5:  1d8913e6935bfe708c5a744a6f405848