In this paper, we have developed a number of analytical models that show the theoretical performance potential of eager writing, the technique of performing small atomic writes near the disk head position. We have presented the virtual log design which supports fast synchronous writes without the semantic compromise of delayed writes or extra hardware support such as NVRAM. This design requires careful log management for fast recovery. By conducting a systematic comparison of this approach against traditional update-in-place and logging approaches, we have demonstrated the benefits of applying the virtual log approach to both UFS and LFS. The availability of fast synchronous writes can also simplify the design of file systems and sophisticated applications. As the current technology trends continue, we expect that the performance advantage of this approach will become increasingly important.