This is an excellent comparison of the pros and cons of different types of SSD deployment. One point I’d like to make sure the reader understands is that many of the limitations of SSD described here are simply irrelevant when it comes to DRAM. DRAM has none of the life limitations of SSD and has far superior write performance. DRAM performance does not degrade over time as Flash performance does and DRAM does not die after a specified number of writes. Like the Energizer bunny, DRAM just keeps working the same way it did on day one. Those are important things to consider when choosing between a flash and DRAM SSD solution. As you mention, it’s also important to understand the superior performance characteristics of purpose built appliances, which are not constrained by the I/O limitations of disk-like architecture.