256GB Performance Testing
You have to reset the clock with 256GB-class products. We had to dig deep into our archives to build these charts. Lithography advancements created higher-capacity NAND die, which in turn require fewer die to construct low-capacity SSDs. SSDs need to access more die at the same time to perform at high speeds, but dense NAND reduces performance because of less NAND parallelization. Due to clever engineering, the performance doesn't cut in half with half the number of die.
Companies don't like to send reviewers products that don't meet "up to" performance numbers. We often see the "up to" performance numbers on the main product page, but the vendors bury the real specifications in the fine print. The smaller drives suffer a significant performance drop off compared to the higher capacity models. If a company uses a single performance rating for a product series, it's often an "up to" specification. That means you need to investigate further. The vendors want to tuck this information away, so lately we don't receive many 256GB-class products.
The Adata Ultimate SU800 uses an SMI SM2258 controller with Micron 3D TLC NAND. It's one of the newest 256GB-class SSDs we've tested. The drive suffers from low performance when data fills the SLC cache. The SSD folds the data into TLC rather than use the newer direct-to-die method. We found the SU800 256GB for $99.99. The Crucial MX200 is an older SSD, but it still sells for $159.99. It's a popular choice for users still looking for MLC NAND, but its price has crept up over the last year. The Mushkin Reactor also features MLC flash and retails for $139.99. The Plextor M6V is available from a very limited number of retailers but has moved on from Amazon and Newegg. It features TLC flash and shows how products from early 2016 compare to newer hardware. Samsung discontinued the 850 EVO 250GB, but both Amazon and Newegg still have inventory. Expect to spend around $109.
Sequential Read Performance
This product class delivers nearly identical sequential read performance compared to the 512GB-class SSDs we tested on the previous page. The SC308 256GB writes data within 1 MB/s of the larger model at QD2.
Sequential Write Performance
We see a lot of variation in sequential write performance. These drives all use distinct types of controllers, flash, and IP. The SK Hynix SC308 isn't as fast as the older products, but it is much better than the SU800 with 3D TLC.
Random Read Performance
We've discussed SSD performance regression for over a year, but the SK Hynix SC308 doesn't suffer from "progress." SK Hynix has 3D flash, but the company hasn't brought the new media to consumer SSDs because the large die is better suited for high capacity drives. Hynix manufactures NAND, so it still has access to planar flash.
Random Write Performance
The SC308 256GB has lower random write performance than the older products, but it still outperforms the Micron 3D NAND in the SU800.
80 Percent Mixed Sequential Workload
Like the 512GB model, the 256GB SC308 doesn't perform well with mixed workloads. At QD2, the SC308 delivers the least bandwidth. Performance increases as the workload intensifies, but it still trails well behind some of the other products.
80 Percent Mixed Random Workload
The SC308's mixed random performance is also lower than many of the other drives. Like before, this will tip back up in the next section with real-world applications.
PCMark 8 Real-World Software Performance
For details on our real-world software performance testing, please click here.
The low mixed random performance will have an adverse impact on the user experience during normal desktop use. An SLC buffer would certainly help to increase performance, but it’s too late to add that to the SC308 design.
Application Storage Bandwidth
The low performance is more obvious when we average the results and present them as throughput data. The SK Hynix SC308 falls to the bottom of the chart.
PCMark 8 Advanced Workload Performance
To learn how we test advanced workload performance, please click here.
Like the larger drive, the SC308 256GB is better during heavy workloads.
Total Service Time
The 256GB SC308 is more competitive than the 512GB model. It's disheartening to see the SC308 suffer from lackluster performance in light- and moderate-use scenarios, particularly because it does so well under heavy use. It's a lot like the Samsung 850 Pro.
Disk Busy Time
We can often tell how an SSD will handle the Notebook Battery Life test by examining the disk busy time. As you will see, that isn't the case with the SC308.
Notebook Battery Life
The SK Hynix SC308 256GB consumes more power than the other SSDs. We observed this behavior with both capacities, but can't explain why. The drives still deliver longer battery time than a hard disk drive, but they don't meet the same high standards set by other flash-based products.
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