Using device write buffers is a promising technique to improve the write performance of solid-state disks. The write buffer not only reduces the write traffic to the flash but also produces large and sequential write bursts to the underlying flash translation layer. This study proposes a new buffer design consisting of a replacement policy and a write-back policy. This buffer monitors how the host workload stresses the flash translation layer upon garbage collection, and dynamically adjusts its replacement and write-back strategies for a good balance between write sequentiality and traffic reduction. Experimental results show that the proposed buffer design outperformed existing approaches by up to 20% under various workloads and flash translation algorithms.