Samsung SSD 850 PRO Solid State Drive Review

By Olin Coles

Manufacturer: Samsung Electronics Co., Ltd.
Product Name: Samsung SSD 850 PRO 256GB
Model Number: MZ-7KE256
Part Number: MZ7KE256HMHA (256GB) MZ-7KE1T0BW (1TB)
Price As Tested: $179.99 (Amazon | B&H | Newegg)

Full Disclosure: The product sample used in this article has been provided by Samsung.

Solid State Drive technology has been revolutionary in that it delivers a very noticeable performance boost that surpasses upgrades to other components. As a result, companies who offer SSDs typically spend small fortunes marketing them to the consumer public. Samsung goes a different route, and relies on proven performance to sale units. This was especially true for the Samsung SSD 840 PRO, which generated its own interest by producing impressive transfer speeds. Powered by their own 32-layer 3D V-NAND technology, the Samsung SSD 850 PRO replaces the 840 PRO solid state drive and delivers up to twice the density and write speed of traditional 20nm planar NAND flash components. In this article, Benchmark Reviews tests the 256GB Samsung SSD 850 PRO against the fastest solid state drives available.

The Samsung SSD 850 PRO offers up to 100,000 IOPS random reads and a 540/470 MBps sequential read/write speed – both made possible by Samsung 3D V-NAND technology and 850 PRO’s MEX controllers. According to Samsung, with the 850 PRO solid state drive in RAPID mode (Real-time Accelerated Processing of I/O Data) users may achieve 200% better write performance speeds than possible with 840 PRO. Samsung Magician software allows users to further enhance performance by processing data on a system level using free PC memory (DRAM) as a storage cache. The 850 PRO provides an industry-leading five-year product warranty, and top-level Total Bytes Written (TBW). Samsung’s 32-layer 3D V-NAND Flash has more than double the endurance compared with conventional 2D planar type NAND flash.

UPDATE: after this article was published Samsung increased their limited warranty to 10-years.

Back in 2013, Samsung was hard at work producing 24-layer 3D V-NAND products for their 840 PRO designed for power users. Samsung was credited with providing “unrivaled performance” in the SATA 6Gb/s interface with the 840 PRO, and now Samsung introduces the SSD 850 PRO with 3D V-NAND components. By changing to a 32-layer cylindrical cell structure that can be stacked vertically, the end result is a smaller footprint with higher density. Samsung RAPID (Real-time Accelerated Processing of I/O Data) mode technology was introduced in the 840 EVO and then 840 PRO last year. Samsung provides Magician 4.4 software with SSD 850 PRO, which uses a new DRAM usage algorithm optimized for maximum memory available for RAPID mode. This new algorithm will utilize up to 25% of system memory for RAPID mode, so a system with 16GB memory will use up to 4GB for Samsung RAPID.

Solid State vs Hard Disk

Despite decades of design improvements, the hard disk drive (HDD) remains the slowest component of any personal computer system. Consider that modern desktop processors typically have a 1 ns response time (nanosecond = one billionth of one second), while system memory responds between 30-90 ns. Traditional hard disk technology utilizes spinning media, and even the fastest mechanical storage products still exhibit a 9 ms (9,000,000 ns) initial response time (millisecond = one thousandth of one second). In more relevant terms, the processor sends the command, but must wait for system memory to fetch data from the storage drive. This is why any computer system is only as fast as the slowest component in the data chain, which is usually the hard drive.

In a perfect world all of the components would operate at the same speed: system memory signals as quickly as the central processor, and the storage drive fetches data as fast as memory. With present-day technology this is an impossible task, so enthusiasts try to close the speed gaps between components as much as possible. Although system memory is up to 90x (9000%) slower than most processors, consider that the hard drive is an additional 1000x (100,000%) slower than memory. Essentially, these three components are as different in speed as crawling (HDD) is to walking (RAM) is to running (CPU).

Solid State Drive technology bridges the largest gap in these response times. The difference a SSD makes to operational response times and program speeds is dramatic, and takes the storage drive from a slow ‘crawling’ speed to a much faster ‘walking’ speed. Solid State Drive technology improves initial response times by more than 450x (45,000%) for applications and Operating System software, when compared to their mechanical HDD counterparts. The biggest mistake PC hardware enthusiasts make with regard to SSD technology is grading them based on bandwidth speed alone. File transfer speeds are important, but only so long as the operational I/O performance can sustain that bandwidth under load.

Bandwidth Speed vs Operational Performance

As we’ve explained in our SSD Benchmark Tests: SATA IDE vs AHCI Mode guide, Solid State Drive performance revolves around two dynamics: bandwidth speed (MB/s) and operational performance I/O per second (IOPS). These two metrics work together, but one may be more important than the other. Consider this analogy: bandwidth determines how much cargo a ship can transport in one voyage, and operational IOPS performance is how fast that ship moves. By understanding this and applying it to SSD storage, there is a clear importance set on each variable depending on the task at hand.

For casual users, especially those with laptop or desktop computers that have been upgraded to use an SSD, the naturally quick response time is enough to automatically improve the user experience. Bandwidth speed is important, but only to the extent that operational performance meets the minimum needs of the system. If an SSD has a very high bandwidth speed but a low operational performance, it will take longer to load applications and boot the computer into Windows than if the SSD offered a higher IOPS performance.