Review: Samsung 845DC EVO 240GB, 960GB SATA SSD
TLC for the Datacenter
A little less than two years ago, Samsung surprised the storage industry by unveiling the world’s first 3-bit MLC, or TLC (Triple Level Cell), NAND based SSD, the Samsung 840. At the time, TLC NAND had already been in use for storage applications such as flash drives and embedded systems, but nobody really thought TLC was viable for SSDs due to TLC’s inherently higher latency and its lower endurance compared to older MLC and SLC technologies.
Despite this, Samsung is now standing behind two generations of TLC based SSDs, proving a number of our initial preconceptions of TLC incorrect – the biggest of which is drive endurance. Unlike cMLC (consumer MLC) which is generally rated at ~3,000 P/E (Program/Erase) cycles, TLC is rated at an estimated ~1,000 – 1,500 P/E cycles (the actual number hasn’t really been revealed by Samsung). While it’s easy to base assumptions of an SSD’s endurance on the NAND’s P/E cycles, this is actually a very bad measure of a SSD’s total endurance. Endurance also depends on a SSD controller’s write algorithms, write amplification, garbage collection routines, and over-provisioning which is why Samsung is capable of claiming that their TLC based 840 SSDs can do 10GB/day and has “…no workload restrictions…” on their 3 year warranty as well.
Now that Samsung has proven TLC NAND on the client side, Samsung is now the first SSD manufacturer to take the same technology to the enterprise with a datacenter oriented derivative of their Samsung 840 EVO they’d creatively like to call the Samsung 845DC EVO.
Samsung 845DC EVO Specifications
|Model||845DC EVO||845DC EVO||845DC EVO|
|Form Factor||2.5″ 7mm SATA||2.5″ 7mm SATA||2.5″ 7mm SATA|
|Capacity||240 GB||480 GB||960 GB|
|Controller||Samsung MEX||Samsung MEX||Samsung MEX|
|NAND||19nm Toggle Mode 3-bit MLC NAND||19nm Toggle Mode 3-bit MLC NAND||19nm Toggle Mode 3-bit MLC NAND|
|Sequential Reads||530 MB/s||530 MB/s||530 MB/s|
|Sequential Writes||270 MB/s||410 MB/s||410 MB/s|
|4K Random Read||87,000 IOPS||87,000 IOPS||87,000 IOPS|
|4K Random Write||12,000 IOPS||14,000 IOPS||14,000 IOPS|
|Interface||SATA 6GB/s||SATA 6GB/s||SATA 6GB/s|
|Warranty||5 Years, 150 TBW||5 Years, 300 TBW||5 Years, 600 TBW|
The Samsung 845DC EVO will come in three capacities – 240GB, 480GB, and 960GB with all three drives available in the 2.5″ 7mm form factor. Similar to Samsung’s consumer grade 840 and 840 EVO, the Samsung 845DC EVO will receive overprovisioning out of the box to help improve both drive endurance and drive performance. Like many drives on the market, the Samsung 845DC EVO will receive ~7% overprovisioning, which is ~3-4% more overprovisioning than its consumer oriented cousins.
As it’s an enterprise grade drive, the Samsung 845DC EVO will receive a 5 year, variable TBW (Total Bytes Written) warranty based on capacity. The 240GB Samsung 845DC EVO is rated at 150 TBW while the 480GB version is rated at 300 TBW and the 600GB version is rated at 600 TBW.
Probably the biggest feature that separates the Samsung 845DC EVO from its consumer oriented cousins is that the 845DC EVO will also receive full data path power loss protection. This will allow the drive to flush the contents of its DRAM cache and any data in flight into non-volatile NAND in the event of sudden power loss to ensure 100% data integrity. This is a feature that’s required for many enterprise server deployments.
Let’s take a closer look at the Samsung 845DC EVO.