Searching biological sequence databases is one of the most routine tasks in computational biology. This task is significantly hampered by the exponential growth in sequence database sizes. Existing parallel sequence search tools such as mpiBLAST have been focusing mostly on parallelizing the sequence alignment computation. However, inefficient handling of input and output data can easily create performance bottlenecks even on supercomputers. In this talk I will present a set of techniques for efficient and flexible data handling in parallel sequence search applications, as well as some experiences and lessons learned from the practice of large scale parallel sequence alignment.