Ssd benchmark reviews9/15/2023 ![]() ![]() SLC caches have a limited size, which creates two tiers of performance - one inside the cache, and one outside a cache. SLC write caching has obvious implications for any benchmark that writes data to the SSD. SLC caching is generally not used by enterprise SSDs because it makes performance less predictable and is detrimental to sustained write performance, but for client and consumer SSDs SLC write caching is now nearly universal: essentially all TLC and QLC SSDs use SLC write caching. This freee up the space in the SLC cache for future use. This process (often called folding) is usually automatically performed by the drive during idle time, where latency is not important. The downside is that data written to SLC NAND must later be re-written into blocks that are operating as MLC/TLC/QLC, storing multiple bits per cell. This is because programming the voltage of an SLC cell can be done in one step and doesn't require as much precision as when storing multiple bits per cell. ![]() this allows the drive to absorb a burst of writes more quickly. By treating a portion of the drive cells as one bit per cell, known as 'SLC mode'. Both of these are slower for writes than 1 bit per cell, or SLC. Modern drives run 3 bits-per-cell, known as TLC, and 4 bits per cell, known as QLC. In a drive, the more bits you write to a cell, the more complex (and slower it is). That's because consumer TLC SSDs rely heavily on SLC caching. (In Micron's most recent earnings call, they shared that their client SSD shipments are now over 90% NVMe by number of bits shipped.) The higher performance allowed by PCIe and NVMe rather than SATA make stunning differences in benchmark scores, but the migration to TLC was actually more significant from the perspective of benchmark design. Both have now taken over: MLC has all but disappeared from the market, and NVMe is the default choice for new systems. When I started reviewing SSDs for AnandTech in 2015, TLC NAND and NVMe were only beginning to creep into the consumer market: TLC at the low end, and NVMe at the high end. Today's SSDs also layer on some extra challenges that make their inner workings even more complicated, and require more sophisticated testing to properly assess.Īnyone remember Intel's X25-M, using 50nm NAND? Today's SSDs are much bigger, faster and cheaper, but their controllers and firmware still need to deal with those issues. All of the fundamental challenges of dealing with NAND flash memory still apply: the inability to make in-place modification to data stored in NAND flash, the disparity between NAND page sizes and erase block sizes, the need for wear leveling and the consequent performance drops when a drive is full are all still relevant. More than a decade later, those articles are still valuable background information on how today's SSDs work. Anand's classic articles from 2009, such as The SSD Anthology and The SSD Relapse, document many of the early challenges SSDs had to overcome on the way to taking over as the mainstream consumer storage technology. To start, we need to review a bit about how SSDs work. It is our hope that this new test suite will be suitable for the next several years of SSD reviews. It covers the goals and rationale behind the design choices, the hardware and software configurations used, and the details of each benchmark and its purpose. This article introduces the new 2021 edition of our consumer SSD test suite. The nature of testing hardware has also changed, especially in light of the need to support the latest technologies like PCIe 4.0, We also find it relevant to more closely resemble the kinds of hardware our readers are now likely to be using. This might be on accident, or as part of a deliberate PR strategy to obfuscate the real world performance behind a 'holy' unified metric. SSDs in general have been getting more complex, so there are more ways for benchmarks to end up being misleading or unrealistic. A lot has changed in the SSD market over the past several years, and our SSD testing methods need to change in response to those trends. The last major update to our consumer SSD benchmark suite was introduced in 2017. ![]()
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |