Samsung SSD 850 EVO (120GB, 250GB, 500GB & 1TB) Review
by Kristian Vättö on December 8, 2014 10:00 AM ESTEndurance: Close to Planar MLC NAND
The big question with every new NAND generation is the endurance. We already saw 6,000 P/E cycles in the SSD 850 Pro and an amazing 40,000 P/E cycles in the SSD 845DC Pro, which proved that V-NAND provides substantially better endurance over today's planar NAND nodes. However, endurance was never really an issue with planar MLC NAND except in the enterprise space, so the 850 EVO with its TLC V-NAND offers a much more interesting insight to the capability of 3D NAND technology.
To test endurance, I put the 120GB 850 EVO through our usual endurance test suite. Basically I just used Iometer to write 128KB sequential data at queue depth of 1 to the drive while monitoring the Wear Leveling Count (WLC) and Total LBAs Written SMART values. The 'Current Value' of the WLC SMART value gives the remaining endurance as a percentage (starts from 99), whereas the 'Raw Data' value indicates the number of consumed P/E cycles. In order to estimate the endurance, I had to find the spot where the increase in 'Raw Data' value decreases the 'Current Value' by one.
| Samsung SSD 850 EVO Endurance | |
| Change in Current Wear Leveling Count Value | 6 |
| Change in Raw Wear Leveling Count Value | 128 |
| Total Data Written | 15,260GiB |
| Estimated Total Write Endurance | 254,325GiB |
| Observed Number of P/E Cycles | 1,987 |
It appears that TLC flavor of V-NAND is rated at about 2,000 P/E cycles. The raw WLC value seems to be based on the user capacity (i.e. 120GB = 1 P/E cycle) because just going by it puts the endurance at ~2,133 P/E cycles (128/0.06), but that doesn't add up with the raw NAND capacity and total data written. However, the estimated total write endurance (which is just 15,260/0.06) suggests that the NAND itself is rated at 2,000 P/E cycles, which would make sense as the number of P/E cycles is usually an even thousand and it's also inline with the increase that the 850 Pro saw (from 3,000 cycles in the 840 Pro to 6,000 cycles).
| Samsung SSD 850 EVO Lifetime Estimation | ||||
| 120GB | 250GB | 500GB | 1TB | |
| Raw NAND Capacity | 128GiB | 256GiB | 512GiB | 1024GiB |
| NAND P/E Cycles | 2,000 | |||
| Raw NAND Endurance | 250TiB | 500TiB | 1000TiB | 2000TiB |
| Lifespan with 20GiB of Host Writes per Day with 1.5x Write Amplification | 23.4 years | 46.8 years | 93.5 years | 187.0 years |
| Lifespan with 100GiB of Host Writes per Day with 3x Write Amplification | 2.3 years | 4.7 years | 9.4 years | 18.7 years |
While write endurance in client workloads was never truly an issue even with planar TLC NAND, the doubled endurance in TLC V-NAND makes it practically impossible to wear out the drive before it has become totally obsolete. Only some very extreme workloads could wear out the smaller capacities before the warranty runs out, but the 850 EVO is a wrong drive for such workloads in the first place. All in all, there should be absolutely no reason to worry about the endurance of the 850 EVO, especially given the endurance ratings Samsung is giving to the 850 EVO (75TB for 120/250GB and 150TB for 500GB/1TB).
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Kristian Vättö - Thursday, December 11, 2014 - link
Hi Simon,Sorry for taking a while to respond -- I had to focus on my finals after I got the review done, so I couldn't catch up with all the comments until now.
The 850 EVO is still a SATA 6Gbps design, so there won't be a SATA Express version of it. There may (and likely will) be an M.2 version coming, although that would also be limited to SATA 6Gbps since M.2 can support both SATA and PCIe interfaces. As for the form factors and capacities, it's impossible to say for sure but technically the 2242 form factor could max out at 512GB and the 2280 at 2TB (assuming double-sided PCB and 16x128Gbit dies per package).
However, the SM951/PM951 will be available sometime next year, although it will be limited to OEM channels again (RamCity saves you, again). That's the PCIe 3.0 x4 NVMe M.2 drive with 3D NAND (SM=MLC, PM=TLC). I don't have any further details at this point, unfortunately.
Regarding other PCIe SSDs, I should know more after CES when I meet with all the companies again and get an update on their schedules, but for now it looks like most designs are aiming at mid-2015 launch.
akula2 - Wednesday, December 10, 2014 - link
850 Pros are my last Samsung SSD products to buy. For the upcoming X99 extreme workstations, I'll to go with:1) SanDisk Extreme Pro 960GB (today $490 vs $600 of 850 Pro). The performance of both SSDs are comparable.
2) Mushkin Scorpion Deluxe 960GB PCI-E SSD: this one decimates all the best SSDs.
3) Intel SSD DC P3700 800GB and 1.6TB models: The King
HisDivineOrder - Wednesday, December 10, 2014 - link
This is the problem with Samsung. When they first came into the market, they blew the competition away with incredible performance, reliability, and pricing.The 840 came with TLC, promising superior pricing with good performance, but in fact pricing was out of whack, putting it way above the 830 that had just left the market. Then 840 Pro took over the high end where only fools dare to tread.
The 850 line (Pro and EVO) raise the prices even higher. It's like Samsung thinks they're the Apple of SSD's and can do whatever they want in pricing. To hell with the competition, people will pay whatever they say.
It's a shame. Way back, I got an 830 because it was a great value. This time around? I waited until Black Friday and picked up a Sandisk after waiting a couple of years for Samsung to remove their head from out of their butt. My 480GB Extreme Pro only cost me $185 and it will last me a good long while.
That could have been you, Samsung. I didn't want to put another brand SSD in my machine. I wanted to have only one Samsung Magician. But Samsung pricing is completely absurd.
So, eh, bye bye, Samsung.
Supercell99 - Sunday, December 14, 2014 - link
They acting like Intel with does Xeon chips, except, Samsung actually has other competition with SSD's. Like you, with my next SSD purchase, I will have to look at other companies as Samsung's $/GB vs the competition has continued to get worse.philipma1957 - Thursday, December 11, 2014 - link
I would like a 1.2th ssd that is really 1.5tb with extra provisioning.I would like it to have good 4k random read writes more then anything.
I have 2 1tb ssds and use them for mac minis.
I use external thunderbolt drives and boot with the 1 tb ssd's the drive in the mini is merely a back up for me. I find I could use a little bigger then 1tb for the video recording I do. Still waiting for a bigger ssd.
harrynsally - Saturday, December 27, 2014 - link
Didn't take long for the MSRP to drop. Was on sale at Newegg and I just bought a 250GB 850 EVO for $114 shipped.Although I previously, purchased two Crucial 256GB MX100s, to use in a couple of older laptops, which installed and continue to run flawlessly, wanted to upgrade the HDD in a new laptop.
Was really conflicted in not buying another MX100, but the better performance specification and 5 year warranty won out.
rvb - Monday, January 19, 2015 - link
Has anyone seen info for the write-block and erase-block sizes for the 1TB 850 Pro? I am intending to RAID 4 of them together, and I want to make sure that my RAID's stride-size is a multiple of the larger of those two values. If they are both something small like 4KiB, then pretty much any larger Pow2 value I choose will be fine. But my only other SSD purchase (OCZ Vertex 4) had a WBS of 8KiB and an EBS of 2MiB. In that case, if I'm going to be writing large files to my RAID, then I think it's useful to know that the EBS is so large, so that I can set my RAID stride-size accordingly.Samsung's "data sheet" for the 850 Pro series neglects to give this information... however, I do note that they only quote random-write performance in terms of 4KB transfers, which may imply that at least their WBS is 4KiB. I just wish I knew for certain, and also the EBS ?
mirkogutic - Saturday, January 24, 2015 - link
Hi, i own 2 of the 120GB Samsung EVO 850.Should I put them in RAID 0 or leave them as separate drives?
It seems that Samsung Magician works only when drives are not in RAID mode.
Also, RAPID mode works only on one drive and when not in RAID.
Nilth - Thursday, April 16, 2015 - link
Sorry for the probably dumb question, but isn't the way turbowrite works detrimental for the ssd longevity? If I understood correctly, (almost) ALL the writes are going to pass through the same "x" GB slc buffer. Isn't that partition going to "wear out" son enough?djdownfawl - Thursday, June 4, 2015 - link
@Kristian VättöAs of today's prices Samsung 850 EVO vs the PRO. Would you recommend buying the EVO or the PRO?