Adata XPG SX930 SSD Review

Adata hits back with a new flagship SSD that incorporates high-endurance eMLC flash and a familiar JMicron controller.

Introduction

Adata's XPG SX family is the company's flagship. It recently updated the line-up with a new XPG SX930 that emphasizes endurance rather than performance.

This is the first time I can remember that an SSD vendor shifted the focus of its top-tier product from speed to endurance. For most users, endurance is an afterthought; most enthusiasts are looking for big performance results, even though the numbers given are almost always irrelevant. As the technology used to manufacture NAND inches closer to single-digit atom insulators, endurance is back in vogue as an SSD selling point.

All indications point to 15/16nm as the final node for 2D flash lithography. The next step is stacked cells, in which density increases come from more layers per die rather than trying to fit the same capacity in a smaller area. With each shrink, the insulator layer, which is vulnerable to wear, gets smaller. This decreases the number of times that a cell can write bits and effectively hold them for a long period of time. NAND makers have developed several innovative ways to combat this issue. One method is to reduce the voltage used to charge the cells. In order to do that, the charge has to be applied for a longer time, thus increasing write latency. We often refer to this method as eMLC flash. It has been around for a long time, and is commonly used in the SSDs aimed at enterprise customers.

Flash branded as MLC+ writes to a section of the MLC die in single-level cell mode. SLC is very easy to read and write; the charge is either on or off. This allows the program or read operation to be a little sloppy compared to MLC or TLC, where accuracy is more important. Random write operations wear out flash faster than sequential operations. The sloppy SLC area catches random write data and passes it along to the MLC area as sequential writes. Since the SLC area needs to retain data for only a short period of time, retention is not a problem.

Over the last year, we've all read reports about SSD endurance, with total bytes written (TBW) reaching numbers well beyond manufacturer ratings. What most of these stories fail to take into account is how long information is retained after the drive is without power. Turned on and under constant use, a SSD may move a massive amount of data, but what good is the drive if it shuts down and data is lost a few days later? Proper endurance testing isn't just about how many bytes you can write to an SSD before it fails. At some point, you need to think about how long the data can be reliably suspended in the gates.

With MLC+, endurance works in the opposite direction. The cache doesn't need to hold information; it's only touched for a brief time. When reading and writing a single bit, operational latency is lower. As odd as it sounds, this increases a product's overall performance and endurance. 

Technical Specifications

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Adata's marketing material conflicts with the flash technology used in its SX930. In some documents, we saw references to eMLC. In others, it was called MLC+. I would say the proper message would be MLC+ flash used to deliver eMLC-like endurance levels. Adata is one of the few companies that purchases Micron flash by the wafer and packages it after a binning process. The packages consequently sport Adata branding and part numbers, so we can't use Micron's flash decoder to dig into their composition.

Paired with the flash is JMicron's JMF670H controller, along with DDR3 DRAM for caching user data and buffering page table information. Previously, we covered the inner workings of the JMF667H with Turbo Boost technology. In that piece, you'll find the complete deep-dive into the controller, complete with a detailed feature set walk-through.

Adata released the XPG SX930 in three capacities: 120GB, 240GB and 480GB, and we have them all in our lab. The company was shy when it came to publishing performance information. The data above comes from official documentation, and you'll notice the lack of random performance figures. Of course, we'll run our own benchmarks to fill in the blanks.

The XPG SX930 supports DevSlp for very low power consumption at rest, but does not support hardware encryption. Most users in the segment this drive family targets don't employ full-disk encryption anyway, so this isn't a big loss for them. 

Pricing, Warranty And Accessories

According to Adata, "The XPG SX930 is designed as a high-end gaming model with excellent reliability and performance." With that said, JMicron positions its JMF670H as a mainstream controller that emphasizes value. We tend to ignore the grandiose claims when it comes to product placement and let the numbers we generate tell us where a product sits in the hierarchy.

MSRP pricing shows the 120GB model at $80, the 240GB version at $110 and the 480GB SX930 at $200. Those figures suggest that Adata's XPG SX930s fall into the popular low-priced mainstream segment.

JMicron's JMF670H controller, capable of correcting up to 72 bits per 1KB of data, paired with the Micron MLC+ makes for a powerful combination. Adata is so confident in it that the SX930 receives a five-year warranty without a specific TBW limit.

Unlike many other mainstream SSDs, the SX930 comes with a full retail accessory package. This includes access to Adata's SSD Toolbox software with features from Acronis. Customers also receive a 7mm-to-9.5mm adapter, a desktop adapter bracket and screws for mounting the drive in their systems. Extensive accessory kits have become rare in recent years, with only a few companies even offering add-on hardware in premium products. Adata is going after gamers, and the accessories help appeal to that market.

A Closer Look

Adata made several changes to the branding of this SSD. Its hummingbird logo is gone, replaced by a much cooler flame design, and the XPG logo now has a HyperX-like aesthetic indicative of a more premium product.

We already mentioned the accessory package, but in this image you get to see what's included with every Adata XPG SX930 SSD. 

We have all three members of the SX930 family to test. In this section, though, we're focusing on the 120GB model.

Aside from the capacity written on the label, the drives are identical from the outside. 

The SX930 uses a 7mm case design, so it will fit in notebooks that require the thinner form factor. Adata includes a 7mm-to-9.5mm adapter bracket if you need it for drive sleds and trays. 

A desktop adapter bracket is also included. Most newer PC cases include mounting options for installing 2.5-inch drives. But many older systems do not. The adapter will come in useful if you need it. 

Inside, we find a half-length PCB that reduces manufacturing cost. The 120GB model uses four flash packages, or half of what the 240GB model has. Adata's 480GB SX930 uses eight packages, just like the 240GB model, but with increased density.

The JMicron JMF670H controller is based on a single-core ARM9 processor and uses Nanya DDR3 for cache and page table mapping.

Adata bins and packages Micron flash in-house. The company's part numbers do not correlate with Micron's, and a public decoder does not exist at this time. 

Data Type Comparison and SLC Cache

We used Anvil's Storage Utilities 1.10 to look for differences in performance between data types. The XPG SX930s do not lose read or write performance when switching between compressible and incompressible information.

In this test, we can see the Write Booster technology working with sequential data. We're using the 120GB model because it shows the largest performance difference between the pSLC and MLC modes. In this particular capacity, you get 4GB of pSLC, which doubles to 8GB on the 240GB model. The 480GB version doubles pSLC again to 16GB. Naturally, the larger the cache, the longer you can write data to the drive before performance drops to the lower level.

The 128GB-class SSDs use eight 128Gb (16GB) dies, and are usually equipped with two dies per package. The leap in price between a 128GB- and 256GB-class drive is not linear, and the greater capacity is almost always a better value due to other material costs. This is why we rarely publish performance data on 128GB SSDs.

Sequential Read

To read about our storage tests in-depth, please check out How We Test HDDs And SSDs. Four-corner testing is covered on page six.

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We're showing all three capacity points in the charts, but comparing the results with other 480GB products. Adata's XPG SX930 480GB costs $200, and its main competitor at that price is the Samsung 850 EVO 500GB, currently selling for $177, though occasional sales take the drive as low as $150.

While Adata's published specifications show all three models at 560 MB/s in sequential reads, there are variations among the three drives in practice. The 480GB model delivers roughly 100 MB/s more read performance than the two smaller models at a queue depth of two. But at QD32, where Adata measures performance, all three versions converge with performance topping 500 MB/s. 

Sequential Write

Adata's documents show the 480GB model achieving 420 MB/s sequential write performance and the two smaller models at 460 MB/s. We think this may be an error on Adata's part or an odd result attributable to the software used for testing. We actually observed the larger SSD delivering more sequential write performance. A bigger pSLC buffer and greater interleaving contribute to the performance advantage. Still, Adata's SX930 480GB falls well short of the other drives in our chart measured using the same methods.  

Random Read

Across the entire queue depth range, the XPG SX930s consistently fall to the bottom of the random read performance charts.

The line graph shows that they fail to scale as well as the competition when queue depth increases, and they also don't achieve high QD1 random read performance at the start of the test.  

Random Write

JMicron has yet to deliver a controller that matches the random write performance results of other processors on the market. Write Booster technology and pSLC modes close the gap somewhat (it was much wider in previous-generation products). Still, though, the random write performance difference between a leader like the 850 EVO 500GB and Adata's SX930 480GB is substantial. 

80 Percent Sequential Read Mixed Workload

Our mixed workload testing is described in detail here, and our steady state tests are described here.

Moving over to mixed workloads doesn't help the SX930 much either. In these tests, Samsung's TurboWrite emulated SLC mode pushes its 850 EVO to the top of the chart. The SX930 480GB starts off strong, but again fails to scale as queue depth increases. A good SSD doesn't slow down when it's asked to perform more tasks at lower queue depths. In fact, you should actually see performance increase, and that just doesn't happen with the SX930. 

80 Percent Random Read Mixed Workload

The initial low random performance carries over to mixed workload random performance as well. Here, we see the SX930 drives isolated at the bottom of the chart, joined by an Intel SSD 530 that uses a SF-2281 controller. This test uses 100 percent entropy (incompressible data), so it's the worst-case scenario for a SandForce processor. That's the level of random performance you can expect from Adata's SX930.

Sequential Steady State

Even entry-level drives raise the bar compared to mechanical disks, absorbing professional workloads fairly easily. Here, we look at heavy sequential performance with the drives in steady state. This test also shows just how much the SX930 relies on caching technology to increase write performance. All of the other products in the chart show a "bathtub curve," with a deep dip in the middle where the workload is mixed, but much higher performance on the edges.

The Adata SX930's steady state write performance never increases after just 10 percent writes are added to the mix. The difference between the SX930 and other products at 100 percent writes is staggering. Under this condition, the pSLC buffers are already full and ineffective.

Random Write Steady State

The random 4KB write steady state benchmark doesn't represent a normal client workload, but when we take the drives down to this level, we can at least gauge performance in a RAID environment. Consistent results like those from Intel's SSD 730 (the purple line) show exactly what we want to see when choosing a drive for RAID.

The SX930 480GB delivers high 4KB write operations at peak in steady state, but fails to maintain the high level. We also observed the 480GB model dropping performance down to 0 IOPS. That is never a good sign; it suggests that you could experience pauses during intensive tasks.

PCMark 8 Real-World Software Performance

For details on our real-world software performance testing, please click here.

Given what we saw in our synthetic benchmarks, it doesn't come as a surprise to see Adata's SX930s at the tail end of the real-world performance tests. These metrics also show just how small the real-world performance difference is between very good SATA 6Gb/s drives and the ones we wouldn't recommend just for their performance alone. 


Total Storage Bandwidth

Now we'll average the results and look at performance in terms of throughput, rather than time. We're really checking to see whether Adata's SX930 can compete with Samsung's 850 EVO.

Given the final tally, unfortunately, we can say the SX930s don't keep up with the 850 EVO in real-world software. 

PCMark 8 Advanced Workload Performance

To learn how we test advanced workload performance, please click here.

The two largest SX930 SSDs recover well after heavy workloads, while the 120GB model doesn't spring back as quickly. Really, it's out of its element compared to the larger versions, though even when it's charted against similarly-sized repositories, the SX930 falls short. 

Latency Test

Isolating latency, the SX930 shows traits that we associate with a poor user experience. Of course, if you're coming from a hard drive, the SX930 does improve responsiveness. But it also fails to improve on Adata's previous-generation SSDs like the SX920 that used a Marvell controller. 

Notebook Battery Life

For more information on how we test notebook battery life, click here.

The SX930 480GB does deliver a little more run time on battery power than the 850 EVO 500GB. For road warriors, this is an important measurement. It's always nice to have enough juice to fly across the country without looking for a place to charge along the way. 

In a reduced-power environment, clock rates are deliberately reduced to conserve power. Most SSDs perform at the same speed under these conditions; the bottleneck shifts to other hardware. 

Conclusion

Even though the SX family hosted Adata's fastest SSDs for several years, the SX930 can be taken seriously only as a value or entry-level drive. The previous-generation SX920, a Crucial M550 clone that was identical in every way, is faster. The SX920 even scaled to 1TB, a capacity the SX930 fails to reach.

With that in mind, we need to look at other products that sell for the same or less to really understand what drive you should purchase. Sticking with 512GB-class SSDs, the Samsung 850 EVO 500GB and Crucial BX100 500GB are gold standards at this price point. As of this writing, both cost $177 at the same reputable online outlet. In our Crucial BX100 500GB review, we stated that, dollar for dollar, Samsung's 850 EVO is a better option. That takes care of the BX100 500GB.

The Adata SX930 does include an old-school accessory package. Many users no longer require a desktop adapter bracket or even the new 7mm-to-9.5mm adapter. Adata includes these parts in the retail SX930 kit, and if you need them you save between $10 and $15, along with a week's worth of shipping time. Adata also includes an SSD Toolbox software package, which makes life easier when you need to take a serious look at your drive and examine its SMART data for issues. The Adata utility also includes a feature for cloning existing data to your new SX930 SSD. The 850 EVO is void of a desktop adapter bracket, but does include software for data migration and enhanced DRAM caching capabilities.

On the performance side, the Adata SX930 compares better to Crucial's BX100 than the 850 EVO. Samsung's 3D V-NAND, even in three-bit MLC mode (TLC), is superior in every way to existing flash from Toshiba and Micron. This all but ensures better performance from Samsung's products, with the only exception being SanDisk's cost-competitive Extreme Pro.

Micron and JMicron are trying desperately to close the gap on Samsung's performance advantage by enabling SLC modes. While MLC+ and JMicron's Write Booster are effective under moderate workloads, the 850 EVO's TurboWrite algorithms are more mature and effective all the way into heavier tasks. The difference is a better user experience through a wider range of applications.

Both the SX930 and 850 EVO feature five-year warranties. Samsung's drive has been available for more than a year now, and we've yet to hear about problems with it. The SX930 may or may not prove to offer the same level of reliability. Since it's new, we can't say one way or the other. This is another area where the 850 EVO's success makes it difficult to recommend a challenger.

Finally we have the price comparison. Adata's SX930 480GB has an MSRP of $200, though at the time of writing, we were unable to find any SX930s for sale. The 850 EVO 500GB sells daily at $177, and we've seen sales that push the drive down to $150. In order to be competitive and make the SX930 480GB a viable option, it'd need to be priced $20 to $30 less than the 850 EVO at 480GB.

When it comes to SATA-based storage, the ceiling was achieved for 6Gb/s on day one. Since then, flash has only gotten worse for performance and endurance. Magic tricks used to make 15nm/16nm as good as 24nm/25nm look good on paper, but those tricks fail to keep pace with older products on the market in real-world use. 3D is on the horizon, but companies need to survive in a Samsung-dominated world until then.

Companies like Adata have to focus on the future and untapped markets. Low-cost NVMe is the only area left for exploration. Spending engineering resources on SATA 6Gb/s is a lost cause when the new flash fails to outperform the product it replaces. Samsung managed to time 3D just right, and the other companies are left to release value-oriented products as flagship offerings. This lack of forward thinking is dangerous for an industry that requires more than one source for competitive hardware to keep pricing in check. We are lucky to have low prices now, but it only comes from the generosity of one company that is far ahead of the others.

Products like the SX930 are only competitive against SSDs built three to five years ago. They do cost less, but when it comes to performance, SATA is going in the wrong direction. The price is good if you're coming from a hard drive, but these drives leave little reason for current SSD owners to purchase new products that offer equal or sub-par performance compared to what they already own.

MORE: Best SSDs For The Money
MORE: Latest Storage News

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Chris Ramseyer is a Contributing Editor for Tom's Hardware, covering Storage. Follow him on Twitter and on Facebook.

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