X99 HPC unboxing 06: Samsung 850 Pro 512GB SSD

morreale Monday 03 of August, 2015
The ASUS Rampage V Extreme (RVE) supports one 4xPCIe 3.0 M.2 SSD interface. I can image Moss from The IT Crowd calling it flipping fast. The M.2 interface provides 32 GB/s transfer rates which is a little more than 5 times faster than the SATA III interface (6 GB/s).

I’m fascinated by the idea of a Solid State Drives (SSD). There are no moving parts, no head crashes, no vibrations to make the case buzz, they’re low power, and they are flipping fast. I really wanted the M.2 4xPCIx 3.0 SSD card for this build. Unfortunately, the M.2 3.0 version wasn’t available when I started buying components for the system. It was to be available in a few months but I could not wait plus the new M.2 v3.0 SSDs were predicted to be very expensive. Thus, it will have to be an upgrade sometime in the future.

I selected a 512 GB Samsung 850 PRO SSD instead. The 850 Pro is still fast and is so fast that the SATA III interface seems to limit its performance. The 512 GB 850 Pro was the fastest SSD when it was introduced. It contains a controller and 3D Vertical NAND Flash memory. The only SSD drives that are faster are the PCIe based SSD drives (see the link to the review at Toms Hardware for performance charts for comparisons to other drives). The 850 PRO SSD is well made, light weight, and has a 2.5 inch form factor. Figure 1 shows the front of the 850 PRO box.

Image
Figure 1 Samsung 850 PRO SSD Box Front

Figure 2 shows the top of the 850 PRO drive.

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Figure 2 Samsung 850 PRO SSD

Figure 3 shows the unboxing video of the Samsung 850 PRO SSD.


Figure 3 Samsung 850 PRO SSD Unboxing Video

Samsung provides the Magician software used to setup and monitor their SSD drives. It has a benchmark tool and Table 1 shows the performance difference between the 850 PRO SSD, a WD RE 2TD hard disk, and a Seagate Barracuda ES.2 hard drive. Each drive is connected a SATA III ports on the RVE.

Table 1 Drive Benchmark
Samsung 850 Pro SSD 512 GB
WD RE 2 TB
Seagate Barracuda ES.2 1 TB
Units
Sequential Read
554
66
28
MB/s
Sequential Write
435
194
35
MB/s
Random Read
86957
462
243
IOPS
Random Write
74266
690
229
IOPS


The 850 PRO is significantly faster than the hard drives on all measures. It is, however, significantly more expensive. The 512 GB 850 PRO was $289 as compared to the 2 TB WE RE drive which cost $150. The SSD is $0.56/GB whereas the hard drive is $0.07/GB. My budget would not support using SSDs to storing all my photographs and video files. So, I opted to use the SSD card to run the OS and application, and use the hard disk(s) for user files.

Windows 8.1 loads very quickly even with the fast boot option disabled as a result of the high speed data transfer rate from 850 PRO. Applications also load very quickly too. Separating the OS and user file between two different drives, however, creates a problem for Windows 8.1. If you redirect user files to another disk, Windows 8.1 objects and if you force it then you could be blocked from upgrading Windows 8.1 in the future. I restored the user files to the default directory and use a manual workaround to use the hard drive(s) for my user files by defining library links for quick access to my files. It works well but I wish that the library directories would stay open like C: drive directories to reduce the time it takes to locate files.

SSD is a great technology but the flash memory wears out after a certain number of writes. Flash memory uses floating gate transistors to store data and a planar floating gate transistor is illustrated in Figure 4.

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Figure 4 Floating Gate Transistor Illustration

When the floating gate contains a charge, a channel forms between the source and drain, and the transistor turns on. When there is no charge on the floating gate, no channel forms and the transistor is off. To program the transistor, the drain is held at ground and a high voltage is placed in the control gate. Charge tunnels through the gate oxide between the drain and control gate so that the charge accumulates on the floating gate. To erase the charge, the control gate is held at ground and high voltage is applied to the drain. Charge on the floating gate tunnels through the gate oxide away through the drain. After repeated programming and erase cycles, the gate dielectric becomes leaky due to trapped charges that accumulate in the gate oxide.

The Samsung 3D V NAND had improved on the planar floating gate design significantly by using a 3D floating gate structure that stores three bits per cell. The flash controller writes data across the memory to distribute writes to keep the average number of cell writes as low as possible to reduce wear out. The 512 GB 850 PRO is rated at 300 TBW (TeraBytes Written). Samsung also states that the drive has a 2 million hour Mean Time Between Failure (MTBF) which is 1.6 time more than the 1.2 million hour MTBF for the 2TB WE RE. In theory, this SSD drive should be more reliable than the hard drive. I’m hopeful but skeptical as I’ve had at least three enterprise grade Seagate drives fail in under 3 years. If all goes as stated in the datasheet, the drive should last 10 years. With a 300 TWB, I could write 82 GB/day for 10 years before the drive failed. Samsung Magician reports that 3.77 TB have been written as of today (133 days) which averages out to about less than 29 GB/day so this is a very good sign of long life reliable drive.

References

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