Meet Samsung's Read-Focused 845DC EVO SSD
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 |
| Interface | 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 |
| Reliability | 2,000,000-hour MTBF | ||
| Warranty | 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.
