Hole is created while decreasing mesh size
 

I am using octree meshing when i decreased mesh size and density form 4 to 2, the new mesh generated has hole in it while generating old mesh it didn't display anything like that.

I thought holes were created if mesh size is large and it can't properly mesh on the corner.. can you clear me up? i am using tetrahedra/prism mesh elements

Thank You in advance!!

Inspect your geometry if there actually is a hole. The octree mesher can handle a hole in geometry as long as its size is smaller then the specified element size. The mesher then will just mesh over the hole. It can deal with dirty geometry. That is why it is also referred to as robust. By reducing it, your element size probably just fell below this critical "hole size".