Final Words From a technological perspective, the new 850 EVO drives do not bring anything new to the table since it's essentially the 2.5' 850 EVO in a smaller form factor, but what it does bring to the market is more selection in mSATA and M.2 form factors using the SATA protocols. There still aren't too many mSATA/M.2 retail drives available, so the 850 EVO adds a lot of value to that segment because it's by far the fastest mSATA/M.2 SSD and in general the 850 EVO is one of the highest performing SATA drives on the market. With that said, I do have some concerns regarding the 1TB model and its performance. Especially the IO consistency with 50-second pauses is worrying.
Samsung 840 EVO - can't erase / partition After installing the Samsung 840 EVO SSD exactly as per the instructions, I booted up the MAC MINI and the drive was visible, but needed formatting to OSX extended (journaled) in order for me to then install OSX on it and then migrate the old HD system and apps to it.
While that won't have any major impact on very light workloads, anything that taxes the drive a bit more may run into the issue, which is basically that the drive stops for up to dozens of seconds (i.e. Your system freezes). Until Samsung fixes that, I would advise against buying the 1TB version unless you have a very light workload (web browsing, email, etc.). I suspect it's fixable through a firmware update, but I'll have to wait for Samsung's reply to be sure of that. Amazon Price Comparison (3/29/2015) 120/128GB 240/250/256GB 480/500/512GB 1TB Samsung 850 EVO mSATA Samsung 850 EVO M.2 - Samsung 840 EVO mSATA Crucial M550 mSATA - Crucial M500 M.2 - Crucial MX200 mSATA -Crucial MX200 M.2 -Plextor M6M mSATA - Mushkin Atlas Deluxe mSATA - The 850 EVO mSATA/M.2 is already available on Amazon and the pricing appears to be fairly competitive. It's not the cheapest mSATA/M.2 drive around, but the premium isn't that significant when taking 850 EVO's feature set into account (5-year warranty, hardware encryption etc.).
All in all, the 850 EVO presents another option to users who are looking for an mSATA or M.2 SSD. It's equipped with the same extensive feature set as its 2.5' sibling, the performance is good and the pricing is fair. As long as Samsung is able to fix the 1TB mSATA on a timely manner, I have no reason not to recommend the 850 EVO. After all, it's still the only mSATA with 1TB capacity. Tuesday, March 31, 2015 - 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 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.).