Abstract: The limited lifespan is the Achilles' heel of solid state drives (SSDs) based on NAND flash. NAND flash has two drawbacks that degrade SSDs' lifespan. One is the out-of-place update. Another is the sequential write constraint within a block. SSDs usually employ write buffer to extend their lifetime. However, existing write buffer schemes only pay attention to the first drawback, while neglect the second one. We propose a hetero-buffer architecture covering both aspects simultaneously. The hetero-buffer consists of two components, dynamic random access memory (DRAM) and the reorder area. DRAM endeavors to reduce write traffic as much as possible by pursuing a higher hit ratio (overcome the first drawback). The reorder area focuses on reordering write sequence (overcome the second drawback). Our hetero-buffer outperforms traditional write buffers because of two reasons. First, the DRAM can adopt existing superior cache replacement policy, thus achieves higher hit ratio. Second, the hetero-buffer reorders the write sequence, which has not been exploited by traditional write buffers. Besides the optimizations mentioned above, our hetero-buffer considers the work environment of write buffer, which is also neglected by traditional write buffers. By this way, the hetero-buffer is further improved. The performance is evaluated via trace-driven simulations. Experimental results show that, SSDs employing the hetero-buffer survive longer lifespan on most workloads.