The power components are also standard for Samsung. It’s expected that the 1TB model would have 1GB. This module is 2GB in size, which matches the 2TB of flash with an ideal ratio. It offers a bit of power savings over traditional DDR. The memory, or DRAM, is Samsung’s LPDDR4 which has been used on many of its SSD products. Samsung has certainly made advances with the controller but other components are more familiar. This can also generally lead to lower latency, although the full benefits are unlikely to be realized on a consumer device. Specific improvements to the controller can increase maximum IOPS by offloading or automating some of this work. The inevitable increase in FTL overhead with more complex algorithms can create a performance bottleneck. Such an algorithm is constrained if it does not take into account spatial locality, that is, knowledge of adjacent and nearby memory locations. Samsung did not elaborate on what it meant by “read caching,” but it is not uncommon to keep some hot data in pSLC to improve forthcoming reads.Ī typical cache algorithm would be least recently used (LRU), where the least recently accessed data would be evicted first from a full cache. In that case, knowledge about the type of data and how it is utilized - metadata - can bolster performance with intelligent caching. Some manufacturers, like Solidigm, have also decided to introduce a form of caching to hold specific data in the cache via a specialized NVMe driver. Write performance often benefits more from such advances, but changes may also be relevant for DirectStorage. Volatile memory like SRAM is used by the controller to cache mapping information and buffer data to commit to the non-volatile NAND flash, so optimization of algorithms can improve overall performance. Separately, parallel processing improvements in firmware can also improve garbage collection/scheduling as with Phison’s I/O+ Firmware. I/O queues and data transfers also benefit from acceleration. One example is hardware-accelerated flash map management which can increase IOPS versus managing the flash translation layer (FTL) - which translates between physical and logical memory addresses - in software. Hardware automation helps overcome these and also offers power savings which is becoming more important as drives get faster. As SSDs scale up to greater levels of parallelization with more complex addressing, IOPS bottlenecks begin to arise. Hardware automation involves the storage data path: the flow of data from the host interface to the flash. Samsung states that this is thanks to an optimized NAND data path through “hardware automation technology” with reduced processing time via a “cache algorithm.” When I asked about the changes, Samsung stated that this architecture was meant to have more effective low-power mode coverage and that it was capable of taking advantage of read caching. There does not appear to be much difference between the controllers superficially, but the Pascal has significantly higher performance specifications. The Pascal is produced in Samsung’s 8nm process node and is still ARM-based. The Samsung 990 Pro sports a new controller, Pascal, as a successor to the 980 Pro’s Elpis. This is more than competitive, exceeding the previous-gen, 980 Pro on all counts but also promising numbers higher than the SK hynix Platinum P41 and WD SN850X. The 990 Pro promises up to 7450/6900 MBps, sequential read and write, with up to 1.4 million / 1.55 million read and write IOPS. The 4TB model is coming later, in 2023 it will be nice to see a larger capacity option from Samsung. The Samsung 990 Pro arrives in the 1TB and 2TB capacities at launch.
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