Next to the 845DC PRO Samsung has also launched the 845DC EVO series. This drive is equipped with TLC NAND flash memory chips and therefore it's suitable for read-intensive workloads, preserving precious write cycles. Furthermore TLC NAND allows for highly competitive pricing, which you will get with this drive. Overall we're curious to see how this drive is going to perform.


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Specifications / Delivery

Model	845DC EVO 240 GB	845DC EVO 400 GB	845DC EVO 960 GB
Capacity	240 GB	400 GB	960 GB
Form Factor	2.5''	2.5''	2.5''
Controller	Samsung 3-core MDX		Samsung 3-core MDX
Memory	MLC NAND 3D V-NAND 2bit		MLC NAND 3D V-NAND 2bit
Throughput	530 MB/s sequential read 270 MB/s sequential write 87'000 IOPS 4K random read 12 '000 IOPS 4K random write	530 MB/s sequential read 410 MB/s sequential write 87'000 IOPS 4K random read 14 '000 IOPS 4K random write	530 MB/s sequential read 410 MB/s sequential write 87'000 IOPS 4K random read 14 '000 IOPS 4K random write
QOS 4KB, QD32 (99.99%)	0.6 ms read 7.0 ms write		0.6 ms read 5.0 ms write
Latency	55 us sequential read 45 us sequential write 115 us random read 55 us random write	55 us sequential read 45 us sequential write 115 us random read 55 us random write	55 us sequential read 45 us sequential write 115 us random read 55 us random write
Power Consumption	2.7 Watt read 3.8 Watt write 1.2 Watt idle	2.7 Watt read 3.8 Watt write 1.2 Watt idle	2.7 Watt read 3.8 Watt write 1.2 Watt idle
Temperature	Operating: 0°C bis 60°C Non-Operating: -40°C bis 85°C	Operating: 0°C bis 60°C Non-Operating: -40°C bis 85°C	Operating: 0°C bis 60°C Non-Operating: -40°C bis 85°C
Endurance	150 TBW	300 TBW	600 TBW
Warranty	5 Years	5 Years	5 Years
Price	249.99 US-Dollar	489.99 US-Dollar	969.99 US-Dollar

Samsung Electronics is finally making a push in the enterprise SSD market whilst also making good headway in the consumer market. First we have the 850 PRO for end-users, then the 845DC PRO and the 845DC EVO enterprise-grade SSDs, which we will be reviewing in this article. In the case of the 850 PRO the most significant upgrade is the NAND Flash, since Samsung is now bringing 3D V-NAND to the mass market, enabling a new level of reliability and endurance. The 845DC EVO is a datacenter optimized SSD with TLC memory, recommended to be used in read-intense environments. You might be asking why Samsung is using TLC NAND in enterprise-grade drives, since P/E-cycle count is much lower than what you get with MLC NAND. As we already mentioned Samsung is targeting read-intensive environments, where P/E-cycle count is secondary if not tertiary.

As already mentioned, Samsung recommends the 845DC EVO for read-intensive environments, therefore sequential as well as random read performance is consitently high, but when it comes to sequential as well as random write performance this drive cannot keep up with the 845DC Pro for instance. In the case of enterprise-grade drives, endurance is usually a main concern. A closer look at rating with the 960 GB 845DC shows a value of 600 TBW, which is just a mere fraction of what you get with the 845DC PRO. What you need to consider with the EVO version is that Samsung is recommending this drive for read-intensive environments, which means write processes aren't of primary concern. 
Another necessary feature of an enterprise-grade SSD is data-path-protection in the case of sudden power-loss. For this purpose there is an array of tantalum capacitors ensuring data residing in the volatile 1024 MB DDR3 buffer can be safely written into non-volatile NAND Flash memory.

Samsung is using the MEX controller for the 845DC EVO SSDs. Compared to the older MDX controller, that's also being used on the 845DC PRO, the new model clockes 100 MHz quicker at 400 MHz. Checking what's going on under the hood reveals there is the same ARM Cortex-R4 based controller there was with the predecessor, which features three cores.

Looking at the exterior of the SSDs, the Samsung 845DC EVO is only available in the 2.5 inch form factor with a height of 7 millimeters. The interface is SATA 3.1, and we're curious to see whether Samsung is planning on releasing a SAS version of this drive. This might be a move demanded by the markets, since the majority of datacenters are built upon SAS infrastructure.

Page 1 - Introduction	Page 7 - Random read KByte/s
Page 2 - Impressions	Page 8 - Random write IOPS
Page 3 - How do we test?	Page 9 - Random read IOPS
Page 4 - Sequential write KByte/s	Page 10 - QD1/4/8/16/32 Performance
Page 5 - Sequential read KByte/s	Page 11 - Conclusion
Page 6 - Random write KByte/s