Documentation for Lustre releases is available:
Supported Lustre Version
Release Date
HTML
PDF
2.x
Latest successful build
Lustre Manual 2.x
2.0
January 2011
Lustre 2.0 Manual
July 2010
n/a
Lustre 2.0 Release Notes
1.8
December 2010
Lustre 1.8 Manual
1.6
June 2010
Lustre 1.6 Manual