Before we get into SanDisk's newest SSD offering, we need to consider where the company has already been. Back in 2008, SMART Modular Technologies acquired a small solid-state drive company called Adtron for $20 million in cash. At the time, SMART primarily focused on memory technologies for embedded computing, primarily for OEMs. Over the next three years, it introduced many different types of SSDs, with IDE, SCSI, and SATA interfaces, built using SLC and MLC flash. In 2011, the company was taken private, and in 2012, SMART was spun-off as an independent entity to better focus its efforts on the growing solid-state drive market. From then on, SMART continued its OEM enterprise business, actively displacing many larger and more entrenched competitors.
SMART Storage Systems may not be a household name, but in enterprise circles, it's well-respected. In the first half of 2013, SMART announced several new products and appeared poised to finish the year with a bang. Then, in June, Western Digital announced the acquisition of STEC, one of SMART's competitors. Just a week later, SanDisk announced its plan to acquire SMART Storage Systems for more than $300 million. In the span of a few days we had two fewer SSD companies.
This wasn't SanDisk's first foray into enterprise storage acquisitions. Back in 2011, the company bought Pliant Technology, which focused on MLC-based enterprise SSDs with SAS interfaces. That deal was also for more than $300 million. So what does SanDisk get this time that Pliant didn't give it? Good question. SanDisk says SMART's products and technologies will complement those acquired from Pliant, including a first SATA-based enterprise-oriented SSD.
All of that history gets us caught up to today. We have the first branded product born out of that acquisition, SanDisk's Optimus Eco SAS SSD. Apparently, the company moved full-speed ahead after closing its deal back in August. After all, our review unit still has all of SMART's old markings, including the distinctive green artwork. This should be the last time anyone sees that, though. When it hits retail, the Optimus Eco will get a SanDisk logo with the corporate color scheme.
| SanDisk Optimus Eco | ||||
|---|---|---|---|---|
| User Capacity | 400 GB | 800 GB | 1.6 TB | 2 TB |
| Interface | 6 Gb/s SAS | |||
| Form Factor | 2.5" 9.5 mm | 2.5" 15 mm | ||
| Sequential Read | 500 MB/s | |||
| Sequential Write | 500 MB/s | |||
| 4 KB Random Read | 95,000 IOPS | |||
| 4 KB Random Write | 35,000 IOPS | |||
| Power Consumption(Active) | 7 W | |||
| Endurance (Drive Writes Per Day) | Three (Random), Seven (Sequential) | |||
The Optimus Eco in an interesting product with a handful of attributes worth pointing out. First, notice those capacity points. We're used to seeing this class of 2.5" drive shipping in 100, 200, 400, and sometimes even 800 GB denominations. The Eco blows right past those numbers, showing up with 400 GB, 800 GB, 1.6 TB, and a massive 2 TB of storage. That flagship easily exceeds the maximum capacity of competing SSDs. But it also comes at a premium price. At the other end of the spectrum, an entry-level 400 GB means you're looking at a sizable investment just to get your foot in the door.
With the exception of the 2 TB model, which is crammed into a 15 mm-tall chassis, the Ecos all ship in a 9.5 mm form factor. The good thing about sporting a SAS interface is that nobody expects your drive to drop into a laptop. And most storage systems with SAS support also accommodate 15 mm drives, since that's the standard for high-speed mechanical disks, too.
Next, check out the drive's performance specs. The word Eco gives off this impression that speed is sacrificed in the name of pricing or efficiency. But that's not the case with SanDisk's Optimus Eco. Its true that you get a slightly lower random write spec than SMART's original Optimus. However, with sequential performance rated at 500 MB/s, and random 4 KB reads rated for 90,000 IOPS and writes at 35,000 IOPS, this shouldn't be a slouch.
But perhaps most shocking (or as shocking as an enterprise-oriented SSD can get), is that the Optimus Eco is still rated for three complete writes per day in random workloads and seven in sequential tasks. Considering it uses 19 nm MLC NAND, not eMLC or SLC, write endurance shouldn't be anywhere near that high. SanDisk apparently has a few tricks up its sleeve, and we'll explore those in today's review.
As with most of these high-end introductions, SanDisk is keeping pricing information fairly quiet. However, its initial announcement did mention that the 2 TB model will sell for $4000. At roughly $2/GB, you pretty much find yourself in the same field as Intel's SSD DC S3700 (Intel SSD DC S3700 Review: Benchmarking Consistency) and Micron's P400m (Micron P400m SSD Review: High Endurance MLC Is Here To Stay). You can expect the lower-capacity versions to command a higher price per gigabyte, but we're hoping they stay in the mid to low $2/GB range.

As mentioned, our review sample is dressed up in its SMART formal wear, while the final version will be decked out as a SanDisk-branded drive. The outer case is die cast aluminum that feels incredibly solid and should help dissipate heat from the components inside.

The chassis is etched so that the highest-power components can make what we think is direct contact. Thermal considerations like this are important in a device that draws upwards of 7 W, but is cooled passively. Interestingly, though, SanDisk doesn't use any interface material between the enclosure and the parts inside. Instead, it appears to rely on the compression force of the assembled SSD.

Looking at the top of the PCB, we see Marvell's controller, front and center. The 88SS9185-BLN2 is part of the very successful 88SS918x processor family. If you've already seen SanDisk's desktop-oriented Extreme II (SanDisk Extreme II SSD Review: Striking At The Heavy-Hitters), then you already know how fast this platform can be.

Next to the controller, you'll find three DDR3-1600 memory packages from Micron. The two larger ones offer 256 MB each, while the third hosts 128 MB. That gives this particular Optimus Eco 768 MB of DRAM cache.

Next, we encounter the 19 nm Toggle-mode MLC NAND sourced from Toshiba (TH58TEG8DDJBA8C). There are 16 total packages, eight on each side, hosting 32 GB each. That means the 400 GB drive actually has 512 GB of flash on-board. We can't say we're surprised; that's actually a pretty common degree of over-provisioning in the enterprise space.

On both sides of the PCB you see big yellow capacitors. Those help deliver power-loss protection. In the event of an outage, data in-flight is committed to non-volatile NAND so that no information is lost.

Like many companies with enterprise-oriented offerings, SanDisk has its own suite of features designed to improve write endurance, data integrity, and the drive's overall reliability. The company groups these technologies under the Guardian umbrella. Individually, they're called FlashGuard, DataGuard, and EverGuard.
FlashGuard
Typical MLC-based SSDs, especially those with sub-20 nm flash like SanDisk's Optimus Eco, you can typically expect endurance rated at less than one complete drive write per day. That's more than enough for most read-intensive environments, but not nearly what you'd want in a taxing write-heavy application. Unfortunately, as manufacturing technology advances, the only way to maintain high-end endurance at the NAND level is paying more for specially-binned eMLC or SLC memory.
SMART, prior to getting purchased by SanDisk, spent years characterizing the behavior of MLC flash and thinks it has the answer. During NAND validation (in this case, 19 nm MLC), data is collected and parameters are calculated to facilitate maximum write endurance per cell. Signal processing is then used to modify those parameters based on the actual performance of each drive once it's in the field.
SanDisk also knows that write endurance varies. Instead of treating every cell as identical, it modifies its wear-leveling algorithm so that stronger cells are exposed to more writes than weaker ones.
The combination of these discoveries and features is why SanDisk is confident its Optimus Eco can withstand three to seven DWPD over the course of its five-year warranty without experiencing write exhaustion.
DataGuard
Also like most other enterprise-class products, the Optimus Eco has a fairly substantial list of reliability-oriented capabilities. It claims to feature improved error detection and correction algorithms to ensure data integrity. SanDisk also offers its F.R.A.M.E. (Flexible Redundant Array of Memory Elements) technology, which allows for cross-die redundancy to safeguard against page or block failure.
EverGuard

As we saw from our photo tour of the Optimus Eco's PCB, the drive employs a number of poly tantalum capacitors to protect against untimely data loss. SanDisk calls this EverGuard. Again, if there is information in flight when the power goes out, the caps provide just enough juice to commit data to memory so that nothing is lost.
| Test Hardware | |
|---|---|
| Processor | Intel Core i7-3960X (Sandy Bridge-E), 32 nm, 3.3 GHz, LGA 2011, 15 MB Shared L3, Turbo Boost Enabled |
| Motherboard | Intel DX79SI, X79 Express |
| Memory | G.Skill Ripjaws Z-Series (4 x 4 GB) DDR3-1600 @ DDR3-1600, 1.5 V |
| System Drive | Intel SSD 320 160 GB SATA 3Gb/s |
| Host Bus Adapter | LSI SAS 9300-8e |
| Tested Drives | SanDisk Optimus Eco SAS SSD 400 GB |
| Graphics | AMD FirePro V4800 1 GB |
| Power Supply | OCZ ModXStream Pro 700 W |
| System Software and Drivers | |
| Operating System | Windows 7 x64 Ultimate |
| DirectX | DirectX 11 |
| Driver | Graphics: ATI 8.883 |
| Benchmark Suite | |
| Iometer v1.1.0 | Four Workers, 4 KB Random: LBA=Full, Span Varying Queue Depths |
| ATTO | v2.4.7, 2 GB, QD=4 |
| Custom | C++, 8 MB Sequential, QD=4 |
| Enterprise Testing: Iometer Workloads | Read | Write | 512 Bytes | 1 KB | 2 KB | 4 KB | 8 KB | 16 KB | 32 KB | 64 KB | 128 KB | 512 KB |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Database | 67% | 100% | n/a | n/a | n/a | n/a | 100% | n/a | n/a | n/a | n/a | n/a |
| File Server | 80% | 100% | 10% | 5% | 5% | 60% | 2% | 4% | 4% | 10% | n/a | n/a |
| Web Server | 100% | 100% | 22% | 15% | 8% | 23% | 15% | 2% | 6% | 7% | 1% | 1% |
The Storage Networking Industry Association (SNIA), a working group made up of SSD, flash, and controller vendors, has a testing procedure that attempts to control as many of the variables inherent to SSDs as possible. SNIA’s Solid State Storage Performance Test Specification (SSS PTS) is a great resource for enterprise SSD testing. The procedure does not define what tests should be run, but rather the way in which they are run. This workflow is broken down into four parts:
- Purge: Purging puts the drive at a known starting point. For SSDs, this normally means Secure Erase.
- Workload-Independent Preconditioning: A prescribed workload that is unrelated to the test workload.
- Workload-Based Preconditioning: The actual test workload (4 KB random, 128 KB sequential, and so on), which pushes the drive towards a steady state.
- Steady State: The point at which the drive’s performance is no longer changing for the variable being tracked.
These steps are critical when testing SSDs. It’s incredibly easy to not fully condition the drive and still observe out-of-box behavior, which may lead one to think that it’s steady-state. These steps are also important when going between random and sequential writes.
For all performance tests in this review, the SSS PTS was followed to ensure accurate and repeatable results.
All tests employ random data, when available. SanDisk's Optimus Eco does not perform any data compression prior to writing, so there is no difference in performance-based data patterns.
For comparison purposes, we evaluated the Eco against the Intel SSD DC S3700 and Seagate 600 Pro. While both of these drives are SATA-based (compared to the Optimus Eco's SAS interface), we believe the comparison remains valid considering each product's specifications relative to the rest of the field, Also, in enterprise environments, the availability of SAS and SATA connections is very similar.

SanDisk claims that its Optimus Eco is well-suited for read-heavy apps, so delivering solid random read results is going to be important. Much like Seagate's 600 Pro, the Eco needs a queue depth of 16 before its performance really starts taking off, though. Beyond that point, it serves up outstanding I/O numbers, topping out in excess of 97,000 IOPS. That bests the rest of the field by nearly 14,000 IOPS.

The story of random write performance is similar, though the results are much closer. SanDisk and Seagate are both slower than Intel's models at lower queue depths. But the Optimus Eco eventually catches up to the SSD DC S3700 800 GB to eke out a win, even if it's only by 1000 IOPS. Overall, we have to give this round to Intel, if only because of its superior performance at low queue depths.

SanDisk's Optimus Eco and Intel's SSD DC S3700 basically achieve the same average response time. They deliver excellent performance and are both clearly ahead of the 200 GB SSD DC S3700 and 600 Pro. Maximum response time is also a near-draw as the 800 GB Intel drive leads by less than one-half of a millisecond.

With one page of testing complete, we're already getting more excited about SanDisk's enterprise-oriented SSD. For almost a year, we've praised Intel's SSD DC S3700 for its excellent performance. But the Optimus Eco is matching it at almost every turn.
Increasingly, we pay close attention to the performance consistency of enterprise-class SSDs. This is what separates a good drive from a great one when all of the corner case testing seems equal. Over the past year, we measured this in terms of large block transfers in our Enterprise Video Streaming section. Armed with this data and our exclusive analysis, the peaks, valleys, and frequency of each become clear. If you look at the information for long enough, you start to see fingerprints for each drive.
We start with large-block transfers because, in enterprise video applications, if you don't buffer or write data fast enough, you can lose it completely. Random 4 KB transfers are slightly more academic, but they also match database transfers more closely. With this sort of workload, you might not lose data, but the system will slow down.
For the following tests, we subject SanDisk's Optimus Eco and Intel's SSD DC S3700 to 25 hours of continuous random 4 KB writes across each drive. We record IOPS every second, giving us 90,000 data points. We then zoom in to the last 60 minutes to more coherently visualize the results.

Again, the Optimus Eco gives Intel's SSD DC S3700 a run for its money. The Intel drive's consistency is slightly better, but SanDisk still does well. Every single one-second average falls between 28,500 and 38,000 IOPS (0.84 and 1.12 ms), while 73% are above 33,000 IOPS.

Looking at a histogram of the data, we see a nice, even distribution. Often when we generate this data, we see a high concentration centered around the vendor's claimed spec, but a non-trivial amount of data landing at higher latency levels. Typically, we attribute that to wear leveling or garbage collection. Even Intel's SSD DC S3700 exhibits some of that behavior.
The Eco isn't like that. Although the S3700 demonstrates better performance consistency, it is only slightly better, and that advantage probably won't be noticeable in real-world apps.
Our next set of tests simulates different enterprise-oriented workloads, including database, file server, Web server, and workstation configurations.
The database workload (also categorized as transaction processing) involves purely random I/O. Its profile consists of 67% reads and 33% writes using 8 KB transfers.

Both Intel drives and SanDisk's Optimus Eco fare similarly when you average them out. Interestingly, though, the Eco enjoys its advantage at the start of this test, in sharp contrast to what we found testing 4 KB blocks of data randomly. Intel's SSD DC S3700 pulls away as queue depths increase, though.

The file server workload, which consists of 80% random reads of varying transfer sizes, yields a clear win in favor of the Eco. Better random and sequential read performance is enough to outpace Intel.

The Web server workload (100% reads, varying transfer sizes) closely follows the results of the file server workload, with the Eco finishing in first place.

Finally, the workstation benchmark (80% reads, 80% random) ends up in SanDisk's favor, particularly at the highest tested queue depths (although the Eco and SSD DC S3700s remain pretty much even up to a queue depth of 32).
These contrived workload tests demonstrate that SanDisk's Optimus Eco is ready to take on the competition in a number of different disciplines. We weren't sure if the Marvell controller, driven by a custom firmware, would hold up to Intel's entirely in-house-developed solution. But the results speak for themselves.
If we could change Intel's SSD DC S3700 in one way, we'd fix its sequential performance. Considering the drive's exceptional showing across the rest of our suite, we never understood why sequential performance ended up being so average.

The Optimus Eco demonstrates no such shortcomings in our sequential read test. It starts off incredibly strong, maintaining a quantifiable lead over Seagate's 600 Pro. At the largest transfer sizes, both the Optimus Eco and 600 Pro top out in excess of 550 MB/s, basically saturating their 6 Gb/s interfaces. Intel's SSD DC S3700 needs those big transfers to even approach 500 MB/s.

Sequential writes aren't as kind to the Optimus Eco. The drive has a hard time getting steady on its feet, and we'd blame shallow queue depths and small transfer sizes for that. As the transfers grow beyond 64 KB, though, SanDisk speeds past the competition on its way to 550 MB/s yet again.
We actually see a lot of drives that claim to be capable of peaking above 500 MB/s in sequential tests, but few able to achieve such a lofty goal in a steady state. The Optimus Eco, however, was just as content writing more than 500 MB/s right out of its box as it was after hours of testing.
Video streaming is a demanding workload within the enterprise space. Companies want more HD streams with higher bit-rates and no stuttering. A storage solution well-suited for enterprise-class video delivery has completely different capabilities than something designed for databases. At the end of the day, you're basically looking for exceptional large-block sequential write performance. You also need a high level of consistency that traditionally isn't seen from consumer SSDs. For a more in-depth analysis, take a look at page 10 of Intel SSD 910 Review: PCI Express-Based Enterprise Storage.
Once the drive is in a steady state, we write its entire capacity 100 times. We use 8 MB transfer sizes and a queue depth of four, recording timestamps for each individual write. The graph below reflects 100-point averaging, so that you can better visualize the results.

After 100 full drive writes, the worst thing we can come up with is one point where the streaming rate dropped to 480 MB/s. In other words, at its lowest point, the Eco's streaming rate dropped to the average attained by Intel's SSD DC S3700 and Seagate's 600 Pro. SanDisk has to be commended for not giving up on sequential performance as it chases big I/O throughput.
Normally you'd see us break down the amount of software and hardware buffering needed to maintain a given streaming rate. However, the Optimus Eco fares so well that the data isn't particularly interesting. At a set point of 550 MB/s, the Optimus Eco, best-case, requires a 60 MB buffer. Worst-case, you're looking at 88 MB. Both of those numbers are incredibly low, considering the set point is 10% higher than what SanDisk specifies the drive for.
Consolidation continues changing the face of the SSD industry. Just as we saw years ago with the mechanical disk space, your options are slowly being whittled down. The general consensus is that companies manufacturing NAND and those with impregnable NAND contracts will be the only ones left standing, aside from the scraps left for more niche players.
Probably the biggest challenge in SSD production is the procurement of NAND. When times are good, everyone wins. But, when the economy turns the other way and NAND supplies dwindle, smaller companies are the first to get cut off. Toshiba would never jeopardize its own products for a third party's, and neither would Samsung or Micron. SSD vendors are always one flash shortage away from disaster, which just isn't tenable.
And that's why the SMART acquisition makes so much sense. SanDisk got its hands on great IP and engineering resources, while SMART gained access to SanDisk and its joint manufacturing venture with Toshiba, Flash Forward. More likely than not, the Optimus Eco was already well on its way to launch before SanDisk stepped in. But now that the two companies are one, we're excited to see how future generations evolve into even more compelling hardware.
Speaking of which, the Optimus Eco is one of the best enterprise drives we have ever tested. It's hard to know where to begin. Steady-state read IOPS that approach 100,000 and 36,000 write IOPS are a good start, even if those figures are less than the flagship Optimus that leveraged 24 nm Toshiba NAND. Sequential performance beyond 550 MB/s, while maintaining great consistency, is another reason to admire what the Optimus Eco can do. A five-year warranty, power-loss protection, and respectable write endurance (for an MLC-based drive, at least) round out the package nicely for us. Finally, don't forget that the Optimus Eco is available in capacities as large as 2 TB. There's not much left for us to critique.
The only two factors that might cause hesitation are physical size and interface support. Although we don't expect Z-height to be problematic, the 9.5 and 15 mm enclosures could be too large for certain enclosures, particularly with newer storage systems offering 7 mm trays. The SAS connector could also keep the Optimus Eco out of more entry-level workstations. Really though, those are concerns about addressable markets, and not the Optimus Eco itself.
Finally, there's the question of whether SanDisk's Optimus Eco is fast enough to unseat Intel's SSD DC S3700 as our favorite all-around enterprise drive. We never reviewed SMART's Optimus, which is technically rated for slightly faster random write rates. However, the Eco is still incredibly quick. Of course, if you're looking for SAS connectivity, then there's no contest; the SSD DC S3700 is SATA-only. If you're looking at sequential performance, then again, the Optimus Eco wins. SanDisk even comes out by a very slim margin in random 4 KB workloads.
However, even though SanDisk does great things with its own NAND, the S3700's HET-MLC memory blows it away with the ability to shoulder 10 drive writes per day. That's a specification you need the original Optimus in order to match. With that point aside, I'd consider SanDisk's Optimus Eco and Intel's SSD DC S3700 to be peers, each performing certain tasks incredibly well and both deserving as much praise as an enterprise storage reviewer can give.
