Samsung 850 PRO

The Samsung 850 PRO was released in June 2014 as Samsung's first V-NAND product aimed at consumers, beating the 850 EVO by a few months. Unlike the EVO model, the PRO used MLC (2 bits per cell) NAND rather than the TLC in the EVO line, which gives it higher write endurance and, in Samsung's case, a 10-year warranty, uncommon for a consumer drive.

The 850 PRO uses Samsung's MEX controller, a three-core ARM design also found in the 840 PRO and 840 EVO. The 32-layer V-NAND eliminates the need for an SLC write cache: MLC at this density sustains write speeds consistently without the performance cliff that TLC drives hit when their SLC buffer is exhausted.

Performance is constrained by the SATA interface rather than the NAND or controller. Sequential speeds land at 550 MB/s read and 520 MB/s write across all capacities except the 128GB, which writes at 470 MB/s due to lower parallelism. Random IOPS top out at 100K read and 90K write — a ceiling for SATA SSDs at the time.

The 850 PRO was positioned as a premium drive and priced accordingly. By 2016 it had been largely surpassed on performance per dollar by the 850 EVO, which offered comparable real-world speeds at a lower price, and by NVMe drives for anyone with an M.2 slot. The 10-year warranty was the primary distinction and selling point in until the 860 PRO replaced it.