Which NAND Technology is Best?
Can MLC Endure Your Data Load?
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Taking all of the above into account, some may be justifiably alarmed that SLC options are vanishing from the SSD market. Many SSD vendors have dropped their SLC offerings entirely, and more seem to be following suit. In its place, many manufacturers now offer “enhanced MLC” (eMLC) products featuring roughly 4X to 6X the endurance of conventional, consumer-grade MLC designs. This advantage springs mostly from cherry picking the NAND for the best-performing parts as well as employing superior write throttling algorithms in the controller. However, even the best throttling approaches still limit performance, with the end result being that SLC still retains up to a 40% performance advantage over eMLC. Moreover, eMLC products rarely reach the 10 drive writes per day duty cycle expected of SLC products.
Temperature can also impact SSD performance and endurance. JEDEC examines the role of temperature in relation to whether a drive is consumer- or enterprise-oriented.
Also keep in mind that 100% sequential read or write throughput numbers shown on drive spec sheets do not accurately reflect real world performance. Many enterprise workloads heavily emphasize random data. When writing such data, SLC drives still retain a 2X to 4X advantage on latency over MLC. MLC drives can only overcome this gap through more expensive memory architectures.
In the end, though, the market decides which technology is “best.” Obviously, MLC (and particularly eMLC) offers many value advantages. As eMLC performance and endurance levels increase, the price premium for SLC becomes harder to justify for a higher percentage of buyers. SLC deserve to continue in the market, but its appeal seems likely to continue diminishing over time. For now, the market appears to need both formats, and it would be unfortunate if SLC were to disappear completely at this point due to insufficient demand.