Taking a closer look at Samsung's lineup of 840 Evo solid state drives shows, there are not only 2.5 inch models but also mSATA cards with up to 1 Terabyte capacity. Today we're having a closer look at the 250 Gigabyte mSATA model and we're rather curious to find out what this piece of hardware is capable of.

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Specifications / Delivery

Model	840 Evo 120 Gigabyte	840 Evo 250 Gigabyte	840 Evo 500 Gigabyte	840 Evo 1000 Gigabyte
Capacity	120 GB	250 GB	500 GB	1000 GB
Form Factor	mSATA	mSATA	mSATA	mSATA
Memory	TLC NAND 19nm ~1'200 P/E-cycles	TLC NAND 19nm ~1'200 P/E-cycles	TLC NAND 19nm ~1'200 P/E-cycles	TLC NAND 19nm ~1'200 P/E-cycles
Throughput	540 MB/s sequential read 410 MB/s sequential write 94'000 IOPS 4K random read 35'000 IOPS 4K random write	540 MB/s sequential read 520 MB/s sequential write 97'000 IOPS 4K random read 66 '000 IOPS 4K random write	540 MB/s sequential read 520 MB/s sequential write 98'000 IOPS 4K random read 90 '000 IOPS 4K random write	540 MB/s sequential read 520 MB/s sequential write 98'000 IOPS 4K random read 90 '000 IOPS 4K random write
Accesstime (read)	< 0.1 ms	< 0.1 ms	< 0.1 ms	< 0.1 ms
Acoustics	no noise	no noise	no noise	no noise
Warranty	3 Years	3 Years	3 Years	3 Years
Price

One of the biggest issues with the Samsung 840 (non Pro) was its sequential write performance of 130 Megabyte per second. Since at this point Samsung just wasn't competitive at all, they really had to do something about this to boost this value into a region where it can compete with for example Crucials M500 SSD. Apart from that Samsung also boosted IOPS performance, when you compare the 840 Evo with the older 840 drives.

At this point you should really ask yourself what kind of sorcery is going on behind the scenes that Samsung was able to triple sequential write performance from one generation to another. The key to success actually has a name: TurboWrite. That's what the new proprietary technology has been called and basically it is an algorithm, which has been implemented into the firmware of the 840 Evo's new MEX controller. TurboWrite can use a small portion of the DRAM chip, which sits next to the controller on the SSD's PCB and emulate SLC NAND flash. As soon as there are data transfers this emulated SLC cache acts as a high performance buffer. In other words, Samsung brought the concept of DRAM caching into the SSD controller, which massively boosts sequential write performance, that used to be the achilles heel of the 840 Evo's predecessor.

Next to an improved controller you also get a reworked software suite from Samsung. The latest version of Magician offers lots of features and it's easy to use even for unexperienced users. It's also exactly this group of users which are being addressed by Samsung with all 840 Evo drives and another point where you can see this is the price. With the 840 Evo Samsung is now attacking everywhere and especially their price level in combination with TLC NAND flash is very aggressively chosen.

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