Backup takes too much time

Hii,

I have win 2003 R2 Server. And Eva HSV200-A with 146 X 14 Bay.
I am using Hp Openview Storage Data Protector A.06.00.

Previously it was taking 6:00 hrs to backup a cluster data. but since last one week it is taking 30:00 hrs to backup. While the data is same.

Plz help me out.