We have a 400GB database in SQL 2008 (compatibility 80) we recently upgrade from SQL 2000. For some reason this database seems to have frequent fragmentation issues. There are quite a few indexes in this database with similar issues listed below, but I will use hist_sku_chn_wk_$pk as an exmaple. The fill factor is set to 80%. It currently has 83,142 pages.
I ran a script each night for the last four nights to check for fragmentation and ran an ALTER INDEX REORGANIZE for anything 5-30% fragmented and and ALTER INDEX REBUILD ONLINE anything over 30%. Here are the fragmentation levels and tasks run each night. These fragmentation levels have only occurred after we upgraded to SQL 2008. We previoulsy ran the same database with realatively the same workload in SQL 2000 and NEVER saw this level of fragmentation before! I have also run the DBCC UPDATEUSAGE. I'm not sure why else to try.
4/26: Frag 95% - REBUILD
4/27: Frag 5% - REORG
4/28: Frag 65% - REBUILD
4/29: Frag 71% REBUILD
Steven Trout