Samsung 845DC EVO SSD Review: 3-Bit MLC Hits The Enterprise

With the introduction of its 845DC EVO, Samsung continues down the path of taking well-received enthusiast-oriented SSDs and customizing them for the enterprise. We run the new drive through a battery of tests in order to determine its strengths.

Sometimes a name is more than just a name, and you can glean a lot of information from the 845DC EVO's model number. As with Micron's M500DC and Intel's SSD DC S3500, the DC stands for data center. Normally, that implies the inclusion of power-loss protection, along with firmware optimized for enterprise workloads. And for anyone familiar with Samsung SSDs, the EVO suffix is a clear indication of what this drive is made of.

Before we get ahead of ourselves, Samsung's 840 EVO was released last summer to a host of good reviews. It offers good performance through some innovative technology, ships at high capacities, and sells for reasonable prices, largely due to its triple-level-cell NAND. Of course, during the past year, you couldn't even mention TLC flash without addressing inherently-lower write endurance, higher latencies, and reliability issues. And that was for a consumer-oriented SSD. Now we have Samsung launching a TLC-based drive for the enterprise market? That's right.

When TLC NAND was first productized, most would-be early adopters worried about its write endurance. Lower P/E cycle ratings scared a lot of folks, and when it came to the very lowest-capacity models, some of those concerns were founded. The issue is that judging an SSD's endurance based on the endurance of a single cell doesn't tell the whole story. Further complicating the situation, most enthusiasts think of two bit-per-cell MLC as good for 5000 to 10,000 cycles, which was true three to four years ago. But today's 20 nm MLC comes closer to 3000.

Although the physics of smaller manufacturing nodes whittles away at write endurance, SSD vendors are combating this in different ways. The first is simply adding more NAND. If the price of flash drops faster than the decrease in write endurance, more NAND can help compensate through greater over-provisioning or higher capacities. It's just simply math at that point, spreading writes out across more cells. Second, consider the ever-changing state of controller firmware. Wear leveling, garbage collection, and TRIM strategies have evolved dramatically, allowing SSD vendors to extend the usable lives of their drives. As a result, we concluded in Samsung 840 EVO SSD: Tested At 120, 250, 500, And 1000 GB that TLC is and should remain a viable technology for consumers. What we want to determine today is whether it's ready for a jump into big businesses.

Apparently, some of the misgivings about TLC hit home at Samsung. This time around, the company isn't calling its memory TLC. Rather, the 845DC EVO sports 19 nm Toggle 3-bit MLC NAND. Doesn't that sound better? And Samsung avoids the issue of write endurance by aiming its latest SSD at environments where reads are most prominent. This class of storage is becoming increasingly crowded; perhaps the most notable recent addition was Intel's SSD DC S3500.

Samsung 845DC EVO
User Capacity
240 GB
480 GB
960 GB
6 Gb/s SATA
Form Factor
2.5" 7 mm
Sequential Read
530 MB/s
Sequential Write
270 MB/s
410 MB/s
4 KB Random Read
87,000 IOPS
4 KB Random Write
12,000 IOPS
14,000 IOPS
Power Consumption(Active Max)3.8 W
Endurance (TBW)
150 TB
300 TB
600 TB
2,000,000-hour MTBF
Five years

The drive's specifications are competitive with other SSDs in the read-oriented space. More interesting, perhaps, is that we're being led to believe that the 845DC EVO beats Intel's potent SSD DC S3500 in almost every category, including endurance (despite the triple-level-cell memory). Intel only claims 140 TBW for its 240 GB model and 275 TBW for the 480 GB version.

At this point, the most significant spec missing is pricing. As with so many enterprise-focused launches, even after we reached out to Samsung for more information, we can't tell you what the 845DC EVO will cost. Consequently, it's going to be really tough to weigh in on its value. But let's put everything into perspective. When Samsung's SM843, the 840 Pro with enterprise tweaks, surface, its was priced aggressively in its segment. The drive sold for slightly more than an 840 Pro, in fact. If the company maintains this delta, the 845DC EVO could become an absolute steal considering that the 840 EVO, at larger capacities, consistently moves at less than $0.50/GB.

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  • SteelCity1981
    So basicly it's the more durable version of the 840 evo much like opertons and xeons are to the FX and core i7 series.
  • Plusthinking Iq
    like we know now after the ssd endurance test samsung is the worst enterprise candidate.
  • drewriley
    Anonymous said:
    So basicly it's the more durable version of the 840 evo much like opertons and xeons are to the FX and core i7 series.

    Yes, that's a fair analogy. Just like the Xeon E3-1275v3 is an i7-4770K, but with ECC support.
  • damric
    I've yet to see an SSD fail due to read/write endurance. I only see them fail when the controller gets bugged, which seems to happen all the time, especially on loss of power.
  • soundping
    I'm guessing this SSD doesn't have to new firmware code that extends life and speed.
  • jase240
    Another win for the EVO. This SSD modified for enterprise workloads makes it a good buy for webservers.

    Hopefully the price will go down after launch, and then I see this being the best choice of webhosts.

    Cheaper and adequate for that workload.
  • Nightmare Twily
    Eh I'll keep my 840 EVO 250GB
  • Nuckles_56
    "Even still, I wand to commend Samsung's execution." (last page 1st paragraph) I guess that is supposed to be want, unless Drew Riley has become a wizard now :D
  • Menigmand
    Commending their execution would be a bit harsh, don't you think?
  • drewriley
    Anonymous said:
    Commending their execution would be a bit harsh, don't you think?

    I'm sure worse things were said about Samsung at WWDC '14 yesterday ;)
  • drewriley
    Anonymous said:
    "Even still, I wand to commend Samsung's execution." (last page 1st paragraph) I guess that is supposed to be want, unless Drew Riley has become a wizard now :D

    Now that you mention it.....
  • eriko
    4KB random write, and average response time.

    Nuff said.

    You'd have to be out your mind to put TLC in a a critical environment.
  • patrick47018
    @eriko everyone's critical environments need a little tender loving care
  • photonboy
    The 845dc isn't necessarily the "worst enterprise candidate"; for one thing it wasn't the bottom in every test.

    For another, it's more about VALUE and that's the main point of the article. I assume the top SSD's in this category were MLC not TLC and also more expensive.