The Samsung SSD 850 EVO mSATA/M.2 Review
by Kristian Vättö on March 31, 2015 10:00 AM ESTSequential Read Performance
Our sequential tests are conducted in the same manner as our random IO tests. Each queue depth is tested for three minutes without any idle time in between the tests and the IOs are 4K aligned similar to what you would experience in a typical desktop OS.
In sequential read performance the difference between drives is rather marginal, but in power consumption we start to see some differences. At 250GB and 120GB the 850 EVO is very efficient, but the 500GB and 1TB are again more power hungry.
Looking at performance across all queue depths doesn't reveal any surprises: at QD2 and higher all drives are practically saturating the SATA 6Gbps interface. What's notable, though, is that the 1TB degrades in performance as the queue depth increases. I wonder if this is a thermal issue (mSATA/M.2 don't have a chassis to use as a heatsink) or just poor firmware optimization.
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Sequential Write Performance
Sequential write testing differs from random testing in the sense that the LBA span is not limited. That's because sequential IOs don't fragment the drive, so the performance will be at its peak regardless.
In sequential write speed the capacity plays a more significant role because the 120GB and 250GB are noticeably behind the 500GB and other higher capacity drives. The poor performance of the 1TB model is once again a surprise, though.
The full graph of all queue depths shows the reason for the 1TB's low performance: it starts high at ~430MB/s, but after that the performance decreases.
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Peichen - Tuesday, March 31, 2015 - link
Shouldn't mSATA/M.2 intereface drives be a lot faster than SATAIII drives due to the much faster interface? I was kinda expecting 1GB/sec. speed consider there are already drive tested at 1.4 and 2.7GB/sec.MrCommunistGen - Tuesday, March 31, 2015 - link
mSATA is SATA in a different formfactor. M.2 can be either SATA or PCI-E. As stated in the article, this drive comes (only) in the SATA form.foxtrot1_1 - Tuesday, March 31, 2015 - link
The interface is still SATA, even if the connector is M.2. I assume PCIe M.2 drives will be coming later.Murloc - Tuesday, March 31, 2015 - link
in a very short time they introduced a bunch of connectors and interfaces and it's all gotten quite confusing.foxtrot1_1 - Tuesday, March 31, 2015 - link
Don't worry, it's not like there's also three different mainstream USB standards with two different plugs. Oh wait.Well, at least we have one agreed-upon display connection, that makes shopping for monitors and graphics cards easier. Oh wait.
lazarpandar - Tuesday, March 31, 2015 - link
That's the great thing about standards, you've got so many to choose from!yslee - Tuesday, March 31, 2015 - link
xkcd #927 puts it very nicely. :PArtuk - Wednesday, April 1, 2015 - link
Niceblanarahul - Tuesday, March 31, 2015 - link
You need yo put /sarcasm tag so people don't get confused.Callitrax - Tuesday, March 31, 2015 - link
One thing you should probably do in M.2 SSD reviews is include how the drives are keyed, preferably in one of the tables. This is important since the M.2 interface is actually 4 semi compatible "standards" (see http://arstechnica.com/gadgets/2015/02/understandi... As a result not all M.2 SSDs will fit in all M.2 slots. This one appears to be both B and M keyed so I think it should be pretty universal, but as an example the Samsung XP941 is only M keyed and thus will not work in the HP Stream Mini's B keyed SSD slot. (Did whoever came up with M.2 make a crappy standard that will cause lots of customer support calls and RMA's when consumers M.2 drives don't work with their M.2 equipped computers? Yes they did.)