The Samsung 950 Pro PCIe SSD Review (256GB and 512GB)
by Billy Tallis on October 22, 2015 10:55 AM ESTFinal Words
Testing of Samsung's 950 Pro revealed some curiosities. Nevetheless, even when showing symptoms of possible thermal throttling, the 512GB sustained respectable performance and in tests that were representative of interactive use it performed extremely well. Users waiting on a full range of Skylake systems to come to the market may need a PCIe to M.2 adapter in order to put the drive in a slot that provides four lanes at PCIe 3.0 speed, but with the added benefit that such adapters can be bought with heatsinks to reduce the chance of triggering thermal throttling.
It's hard to judge pricing when there are limited options in this market segment. The Intel SSD 750 clearly needs to come down in price to be completely sidelined by the 950 Pro. Comparing against SATA drives, the 950 Pro's impressively high scores seem to make a good case for its price premium, but consider how often a particular use case will actually be able to take advantage of the peak speeds offered, which makes the 950 Pro a more prosumer oriented product. The 950 Pro isn't for everyone, and if cost is a sensitive issue then the 950 Pro should be weighed against Samsung's other offerings. But simply for a top of the line drive, the 950 Pro is priced reasonably for enthusiasts.
As a sign of where the SSD market is going, the 950 Pro clearly shows that SSD performance can be improved. Before too long, "high-end SATA SSD" will be an oxymoron; it's time for the transition to PCIe! The transition to NVMe seems less urgent given what Samsung was able to do with the SM951 and XP941 using AHCI, especially due to compatibility and drivers at this time. The power management issues in particular will need to be taken care of before NVMe moves beyond the enthusiast segment, especially for mobile computing.
The PCIe 3.0 x4 interface certainly gives the drive plenty of headroom. And based on the performance of the 950 Pro, it's doubtful that an M.2 drive will be able to saturate the interface before running in to thermal limits while still remaining in the same form factor. Future drives in this area will probably have to implement aggressive power saving techniques in order to keep average temperatures low enough to accommodate bursts of activity. The 950 Pro and the PCIe ecosystem in general have a lot to improve upon here.
The M.2 form factor is also constraining drive capacities to a degree. The back side of the 950 Pro is empty so a 1TB model should be geometrically possible if not economical, but the extra NAND packages would be even more susceptible to thermal problems. Samsung is instead choosing to wait for their 256Gb third-generation V-NAND before offering a larger model of the 950 Pro.
So far, Intel is the only manufacturer that has produced an enthusiast drive using the U.2 connector to provide PCIe x4 to a 2.5" drives. U.2 support is far less common than M.2, but the next time Samsung wants to introduce a major performance boost, they may go for the 2.5" U.2 option. We have already seen U.2 connectors directly on a pair of ASUS motherboards announced this week, and a number of Skylake consumer motherboards will come with M.2 to U.2 adapters specifically for this purpose.
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Der2 - Thursday, October 22, 2015 - link
Wow. The 950. A BEAST in the performance SHEETS.ddriver - Thursday, October 22, 2015 - link
Sequential performance is very good, but I wonder how come random access shows to significant improvements.dsumanik - Thursday, October 22, 2015 - link
Your system is only as fast as the slowest component.Honestly, ever since the original x-25 the only performance metric I've found to have a real world impact on system performance (aside from large file transfers) with regards to boot times, games, and applications is the random write speed of a drive.
If a drive has solid sustained random write speed, your system will seem to be much more responsive in most of my usage scenarios.
950 pro kind of failed to impress in this dept as far as I'm concerned. While i am glad to see the technology moving in this direction, I was really looking for a generational leap here with this product, which didn't seem to happen, at least not across the board.
Unfortunately I think i will hold off on any purchases until i see the technology mature another generation or two, but hey if you are a water-cooling company, there is a market opportunity for you here.
Looks like until some further die shrinks happen nvme is going to be HOT.
AnnonymousCoward - Thursday, October 22, 2015 - link
> Your system is only as fast as the slowest component.Uhh no. Each component serves a different purpose.
cdillon - Thursday, October 22, 2015 - link
>> > Your system is only as fast as the slowest component.>Uhh no. Each component serves a different purpose.
Memory, CPU, and I/O resources need to be balanced if you want to reach maximum utilization for a given workload. See "Amdahl's Law". Saying that it's "only as fast as the slowest component" may be a gross over-simplification, but it's not entirely wrong.
xenol - Wednesday, November 4, 2015 - link
It still highly depends on the application. If my workload is purely CPU based, then all I have to do is get the best CPU.I mean, for a jack-of-all-trades computer, sure. But I find that sort of computer silly.
xype - Monday, October 26, 2015 - link
Your response makes no sense.III-V - Thursday, October 22, 2015 - link
I find it odd that random access and IOPS haven't improved. Power consumption has gone up too.I'm excited for PCIe and NVMe going mainstream, but I'm concerned the kinks haven't quite been ironed out yet. Still, at the end of the day, if I were building a computer today with all new parts, this would surely be what I'd put in it. Er, well maybe -- Samsung's reliability hasn't been great as of late.
Solandri - Thursday, October 22, 2015 - link
SSD speed increases come mostly from increased parallelism. You divide up the the 10 MB file into 32 chunks and write them simultaneously, instead of 16 chunks.Random access benchmarks are typically done with the smallest possible chunk (4k) thus eliminating any benefits from parallel processing. The Anandtech benchmarks are a bit deceptive because they average QD=1, 2, 4 (queue depth of 1, 2, and 4 parallel data read/writes). But at least the graphs show the speed at each QD. You can see the 4k random read speed at QD=1 is the same as most SATA SSDs.
It's interesting the 4k random write speeds have improved substantially (30 MB/s read, 70 MB/s write is typical in SATA SSDs). I'd be interested in an in-depth Anandtech feature delving into why reads seem to be stuck at below 50 MB/s, while writes are approaching 200 MB/s. Is there a RAM write-cache on the SSD and the drive is "cheating" by reporting the data as written when it's only been queued in the cache? Whereas reads still have to wait for completion of the measurement of the voltage on the individual NAND cells?
ddriver - Thursday, October 22, 2015 - link
It is likely samsung is holding random access back artificially, so that they don't cannibalize their enterprise market. A simple software change, a rebrand and you can sell the same hardware at much higher profit margins.