ADATA SP550 SATA III (120GB, 240GB & 480GB) SSD Review

Introduction

The SP550 gives us our first look at Silicon Motion's newest controller, the SM2256, in a retail package. The SM2256 is a third party controller designed for use with TLC Flash. We've been testing a reference design from SMI that employs an SM2256 controller with Toshiba A19nm TLC flash, and it performs quite well. We will be including the reference design in this review as a point of comparison.

The SMI SM2256 controller is specifically designed to deliver acceptable SSD performance with next gen TLC Flash. The key feature of SMI's 2256 controller is LDPC (Low-Density Parity-Check) bit correction. SMI calls their proprietary LDPC bit correction engine NANDXtend. NANDXtend error correction and data protection technology triples the P/E (Program/Erase) cycles for TLC SSD devices. This is very important because with conventional ECC correction typical TLC flash is limited to about 500 P/E cycles. With NANDXtend technology (LDPC) TLC P/E endurance is tripled to about 1500 P/E cycles or about half that of today's 3000 P/E MLC flash.

Extending endurance through LDPC bit correction is the most important feature of the SM2256 controller because this gives TLC (Triple Level Cell) flash enough endurance to make it a viable option. Second on the list of features that make TLC viable, is the implementation of an SLC (Single Level Cell) programmed caching layer to mask the extremely low write performance of TLC flash. The SM2256 enables PSLC (Pseudo SLC) programming on TLC flash. A PSLC caching layer is important for TLC SSDs as an acceleration layer, but also it enhances endurance by sequentializing cached data before writing it to the drives TLC programmed flash array and that lowers write amplification.

As mentioned this is not only our first look at the SMI SM2256 controller, the SP550 affords us our first look at SK Hynix 16nm TLC toggle mode flash. On paper, the SP550 looks like it has the ingredients to deliver decent performance and plenty of endurance for typical use cases. Let's get into the review and see what the SP550 is capable of delivering. All three capacity points will be covered in this review.

Specifications: ADATA SP550 SATA III SSD

The SP550 SATA III 2.5" x 7mm FF SSD is available in three capacities: 120GB, 240GB and 480GB. Sequential read performance for the SP550 is listed as up to 560 MB/s. Sequential write performance varies by capacity from 410 MB/s up to 510 MB/s.

Random 4K read performance varies by capacity from 60,000 up to 75,000 IOPS. Random 4K write performance varies by capacity from 70,000 up to 75,000 IOPS. MTBF comes in at 1.5 million hours. ADATA backs the SP550 with an industry standard 3-year warranty. No TBW is given.