This sounds completley normal form what i remembe about mergeFactor. Segmenets are merged "by level" meaning that with a mergeFactor of 5, once 5 "level 1" segments are formed they are merged into a single "level 2" segment. then 5 more "level 1" segments are allowed to form before the next merge (resulting in 2 "legel 2" sements). Once you have 5 "level 2" sements, then they are all merged into a single "level 3" segment, etc...
: I had my mergeFactor as 5 , : but when i load a data with some 1,00,000 i got some 12 .cfs files in my : data/index folder . : : How come this is possible . : in what context we can have more no of .cfs files -Hoss