This spring has turned out to be the time for nearly all SSD OEMs to update their lineups. A little over a month ago Intel introduced the SSD 730 and a bit over a week ago Crucial/Micron added the M550 to its portfolio. Today it's ADATA's time to join the game with their Premier Pro SP920...and FYI, there will be no April Fools jokes here.

While we are still a quarter or two away from wider availability of PCIe drives and the next big wave of SSDs, the recent product releases in the NAND department have made it economically reasonable for OEMs to update their drives. Both IMFT's 128Gbit 20nm MLC and Toshiba/SanDisk's second generation 64Gbit 19nm NAND are now available in volume, and given the higher density and thus lower price, it makes sense for tier two OEMs (i.e. the ones without NAND fabs) to adopt the new NAND into their products.

The SP920 is actually the first non-Crucial/Micron SSD to use Micron's 128Gbit 20nm MLC NAND. As a matter of fact, the SP920 adopts far more than just the 128Gbit 20nm NAND from Micron—the SP920 is more or less a rebranded M550. Everything from the PCB and chassis designs to the component choices are a match with the M550. In fact, even the firmware in the SP920 is listed as "MU1", which is the same as in the M550 and Crucial/Micron in general is known to use MUx firmware names. Thus, we're basically looking at a rebranded M550.

The only difference between the SP920 and M550 is that the SP920 uses 128Gbit NAND in all models, whereas the M550 only uses that in the 512GB and 1TB models and the smaller capacities use 64Gbit NAND. That gives ADATA a slight price advantage (128Gbit die has higher density and is thus cheaper) but in turn the performance of 128GB and 256GB models is worse due to fewer dies. At the bigger capacities ADATA is a bit more optimistic with the performance figures, which is something that's fairly common for the tier two OEMs. The likes of Intel, Crucial/Micron and Samsung like to be conservative and round the numbers down, whereas smaller OEMs will advertise every single IOPS and MBps they can get out of the drive.

ADATA obviously can't comment on the similarity for contract reasons but they are not denying that the SP920 is rebrand. They did disclose that the firmware is from a third party, which further confirms that we are looking at an M550 with different branding.

I'm generally not a big fan of rebrands because they don't really bring anything new to the market but I do see the business reasons behind it. In order for companies to be profitable, they must focus on their core competence and the actual product doesn't have to be that. If your sales channels or marketing for instance are more efficient that your competitors', you may be able to sell the exact same product and make more profit than the others. I have no doubts that ADATA has better sales channels in Asia and other markets close to its home ground and hence it can be viable to sell a rebranded drive. In the end, more competition is always welcome.

Similar to the M550, the SP920 features full support for Microsoft eDrive thanks to TCG Opal 2.0 and IEEE-1667 standards. Power loss protection is also included. Since the SP920 is almost an exact copy of the M550, please read our M550 review for more in-depth coverage of the included features and their purposes. As for the ADATA SP920, the main difference we'll see here is in performance of the 128GB and 256GB models, so let's get to the benchmark.

EDIT: The SP920 doesn't actually support TCG Opal 2.0 or IEEE-1667. This seems to be a feature Micron is keeping to themselves. 

Performance Consistency

Performance consistency tells us a lot about the architecture of these SSDs and how they handle internal defragmentation. The reason we don’t have consistent IO latency with SSD is because inevitably all controllers have to do some amount of defragmentation or garbage collection in order to continue operating at high speeds. When and how an SSD decides to run its defrag or cleanup routines directly impacts the user experience as inconsistent performance results in application slowdowns.

To test IO consistency, we fill a secure erased SSD with sequential data to ensure that all user accessible LBAs have data associated with them. Next we kick off a 4KB random write workload across all LBAs at a queue depth of 32 using incompressible data. The test is run for just over half an hour and we record instantaneous IOPS every second.

We are also testing drives with added over-provisioning by limiting the LBA range. This gives us a look into the drive’s behavior with varying levels of empty space, which is frankly a more realistic approach for client workloads.

Each of the three graphs has its own purpose. The first one is of the whole duration of the test in log scale. The second and third one zoom into the beginning of steady-state operation (t=1400s) but on different scales: the second one uses log scale for easy comparison whereas the third one uses linear scale for better visualization of differences between drives. Click the buttons below each graph to switch the source data.

For more detailed description of the test and why performance consistency matters, read our original Intel SSD DC S3700 article.

	ADATA SP920	Crucial M550	Intel SSD 730	SanDisk Extreme II	Samsung SSD 840 EVO
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25% Spare Area					-

As expected, the IO consistency is the same as in the M550 and even the capacity variations and over-provisioning behavior match. Like I said in the M550 review, I'm not very satisfied with the IO consistency compared to what we've seen lately but at least ADATA is positioning the SP920 as a mainstream value drive.

	ADATA SP920	Crucial M550	Intel SSD 730	SanDisk Extreme II	Samsung SSD 840 EVO
Default
25% Spare Area					-

	ADATA SP920	Crucial M550	Intel SSD 730	SanDisk Extreme II	Samsung SSD 840 EVO
Default
25% Spare Area					-

TRIM Validation

To test TRIM, I took a secure erased 128GB SP920 and filled it with sequential data. Then I tortured the drive with 4KB random writes (QD32) for 40 minutes followed by a TRIM command (quick format in Windows). Finally I measured performance with HD Tach to bring you the graph below:

And as you should expect, TRIM works.

AnandTech Storage Bench 2013

Our Storage Bench 2013 focuses on worst-case multitasking and IO consistency. Similar to our earlier Storage Benches, the test is still application trace based—we record all IO requests made to a test system and play them back on the drive we're testing and run statistical analysis on the drive's responses. There are 49.8 million IO operations in total with 1583.0GB of reads and 875.6GB of writes. I'm not including the full description of the test for better readability, so make sure to read our Storage Bench 2013 introduction for the full details.

We are reporting two primary metrics with the Destroyer: average data rate in MB/s and average service time in microseconds. The former gives you an idea of the throughput of the drive during the time that it was running the test workload. This can be a very good indication of overall performance. What average data rate doesn't do a good job of is taking into account response time of very bursty (read: high queue depth) IO. By reporting average service time we heavily weigh latency for queued IOs. You'll note that this is a metric we've been reporting in our enterprise benchmarks for a while now. With the client tests maturing, the time was right for a little convergence.

Surprisingly the 256GB SP920 is faster than 256GB M550 even though the SP920 has fewer NAND dies. The main reason Crucial went with 64Gbit die for 128GB and 256GB models was increased performance, but it looks like that mainly applies the 128GB version. Of course, ~10MB/s isn't a big difference but it's still interesting that the performance hit from 128Gbit NAND is mostly a non-issue for the 256GB model.

Random Read/Write Speed

The four corners of SSD performance are as follows: random read, random write, sequential read and sequential write speed. Random accesses are generally small in size, while sequential accesses tend to be larger and thus we have the four Iometer tests we use in all of our reviews.

Our first test writes 4KB in a completely random pattern over an 8GB space of the drive to simulate the sort of random access that you'd see on an OS drive (even this is more stressful than a normal desktop user would see). We perform three concurrent IOs and run the test for 3 minutes. The results reported are in average MB/s over the entire time.

Here you can clearly see the disadvantage of 128Gbit NAND. While the 128GB M550 is nearly able to match the bigger capacities, the 128GB SP920 is noticeably slower. It still offers better performance than a few competing 120/128GB class SSDs, but there are plenty of faster options.

Sequential Read/Write Speed

To measure sequential performance we run a 1 minute long 128KB sequential test over the entire span of the drive at a queue depth of 1. The results reported are in average MB/s over the entire test length. Read speeds tend not to drop as much with fewer NAND die, so the SP920 128GB looks similar to the other SP920 capacities here.

The same isn't true of sequential write performance—at 256GB there is only a minor decrease over bigger capacities but the 128GB offers about half the throughput of the other SSDs.

AS-SSD Incompressible Sequential Read/Write Performance

The AS-SSD sequential benchmark uses incompressible data for all of its transfers. The result is a pretty big reduction in sequential write speed on SandForce based controllers. Here, the M550 ends up quite a bit faster than the SP920 at the lower capacities in the write test, though both are still faster than the M500.

Performance vs. Transfer Size

ATTO is a useful tool for quickly benchmarking performance across various transfer sizes. You can get the complete data set in Bench. The write graph once again shows the performance decrease at smaller capacities—the 128GB only manages ~180MB/s and the 256GB does twice that while others are able to reach 500MB/s.

Click for full size

AnandTech Storage Bench 2011

Back in 2011 (which seems like so long ago now!), we introduced our AnandTech Storage Bench, a suite of benchmarks that took traces of real OS/application usage and played them back in a repeatable manner. The MOASB, officially called AnandTech Storage Bench 2011 - Heavy Workload, mainly focuses on peak IO performance and basic garbage collection routines. There is a lot of downloading and application installing that happens during the course of this test. Our thinking was that it's during application installs, file copies, downloading and multitasking with all of this that you can really notice performance differences between drives. The full description of the Heavy test can be found here, while the Light workload details are here.

While the tests are now approaching three years old, the data they provide can still be meaningful. Despite the names, both the Heavy and Light workloads represent less strenuous loads than our 2013 suite, and the result is a tighter clustering of scores amoung the various drives. If you're a "typical" user and don't really stress your storage subsystem, most modern SSDs feel plenty fast, but there's still a pretty big drop off in responsiveness when we go below the 240/256GB mark. The SP920 again falls behind the M550 at both the 128GB and 256GB capacities here.

Power Consumption

Only the 128GB model has slightly lower power consumption under load than the M550 due to fewer dies but otherwise the power characteristics match with the M550 as expected. Interestingly, the measured idle power of the SP920 is actually higher on the lower capacity models. However, the idle power consumption figures you see here are for desktops with HIPM+DIPM disabled. I now have a way to measure idle power consumption with HIPM+DIPM enabled but due to time limits I don't everything ready for this review. We have another review coming next week, so stay tuned for better idle power consumption numbers.

Final Words

To be honest, I don't have much to add to the conclusion of the M550 review. At 512GB and 1TB, the SP920 is an exact match with the M550. The 128GB and 256GB models lose some performance compared to the M550 due to fewer NAND dies but especially at 256GB the difference is rather insignificant. The only things that the SP920 have that the M550 doesn't are a license for data migration software and a 3.5" adapter. Whether these are something you consider valuable is totally up to you, but nowadays most cases have screw holes for 2.5" drives and data migration can be executed with freeware tools, so neither is exactly a must have feature.

In terms of pricing the SP920 is extremely competitive. The usage of 128Gbit NAND gives the SP920 a slight pricing advantage at 128GB and 256GB compared to the M550 but at 512GB and 1TB the MSRPs are the same as the M550. It will be interesting to see how the prices play out in the future—on one hand it doesn't make sense for Crucial/Micron to price the M550 higher because they should have a manufacturing cost advantage but on the other hand tier two OEMs (like ADATA) are known to be pretty aggressive on the pricing front and are not afraid of selling at a loss in the short term.

All in all, I would've liked to see something more customized from ADATA but a rebranded value drive suffices too. As I've said before, in the mainstream segment it's all about price and if the MSRPs give any hint, the SP920 (along with the M550 of course) can be very competitive there. The SF3700 is supposed to bring more customization options for OEMs, so focusing the R&D resources on it and the high-end drives doesn't sound like a bad option.