The Samsung 950 Pro PCIe SSD Review (256GB and 512GB)
by Billy Tallis on October 22, 2015 10:55 AM ESTMixed Random Read/Write Performance
Most real-world use consists of a mix of reads and writes, and interleaving the two often poses a particular challenge to drive controllers. This mixed random access test is conducted across a 16GB span of the drive, but on a full drive and with a queue depth of 3.
Mixed random access seems much improved over Samsung's earlier M.2 drives, and the 950 Pros fall behind only the Intel SSD 750. The 512GB drive is well behaved here and surpassing the 256GB drive as it should.
In this case, the higher power consumption of the 950 Pro is very well justified by the higher performance.
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There's not much variation across the different workloads. Performance hardly drops during the middle of the test where many controllers have trouble with a balanced mix, but on the other hand the performance at either end of the test is nothing spectacular. Power consumption climbs hand in hand with the proportion of writes, but is accompanied by some increasing in overall data rate.
Mixed Sequential Read/Write Performance
The queue depth of 3 is sufficient for many drives to perform very well at either end of this test, while testing 100% reads or 100% writes. In between, performance typically suffers greatly, and that's where the winners and losers of this test are determined. Anything that's duplicating duplicating or transforming a large amount of data on the drive will produce I/O patterns similar to this test. Creating a System Restore snapshot, backing up files to a different directory on the same drive, and file compression can all produce interleaved reads and writes of large blocks of data, though not necessarily fast enough to be limited by the drive's performance.
These sequential workloads allow the PCIe drives to stand out and achieve average speeds that would saturate SATA.
With power consumption in the same neighborhood as the SATA drives, the 950 Pro is significantly more efficient.
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Looking at the breakdown by workload, the 950 Pro performs well on the balanced mixes and far outstrips the SATA limit on the very read-heavy workloads and the pure write section at the end of this test.
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Billy Tallis - Thursday, October 22, 2015 - link
If I'd had more time, I probably would have done more informal testing on some older machines. I can at least assure you that the drive doesn't seem to have any trouble in a PCIe 2.0 x2 M.2 slot on my personal Haswell machine. Next time I'm poking around in my Lynnfield server I'll be checking how the pcie drives work, especially power management. But I probably won't do a full suite of performance tests, just enough to get a rough idea for how fast drives perform on a slower link. And I really don't have a clue when I'll get around to this, because I've still got quite the backlog of drives to review.hansmuff - Thursday, October 22, 2015 - link
Understandable, thanks for the PCIe 2.0 update.The_Assimilator - Thursday, October 22, 2015 - link
Thermal throttling is disappointing but shows that M.2, like SATA Express, is DOA. PCIe drives with heatsinks, or preferably U.2, is the future - hopefully with the Z200 series chipsets, manufacturers will ditch SATAe in favour of U.2 and we can finally get a worthy successor to SATA3.MrSpadge - Thursday, October 22, 2015 - link
DOA it certainly is not. You're free to attach a tiny RAM heatsink on the drive and be fine. Or simply forget about throtteling in real world usage (unless you use it in a server).Redstorm - Thursday, October 22, 2015 - link
Under a normal client workload you don't get anywhere near triggering the thermal protection so adding heat sinks is not required. Agree SATA Express was still born. M.2 is far from it, if you look at any new release ultrabook you will find a M.2 SSD under the lid.The_Assimilator - Friday, October 23, 2015 - link
M.2 is a great solution for replacing 2.5" SSDs in space-limited applications like ultrabooks, but for *absolute maximum performance without thermal throttling*, 2.5" U.2 drives a la Intel's 750 are still the way to go.zodiacfml - Sunday, October 25, 2015 - link
It depends on the designer on how much throttling they would allow or not. U.2 allows more freedom though but I reckon would be much more expensive and less dense in the future.user_5447 - Thursday, October 22, 2015 - link
Why everyone keep saying that BIOS/UEFI must support NVMe to boot into OS?You can install GRUB bootloader on cheap small USB flash drive and use it to boot from NVMe drives on any system, since GRUB itself supports NVMe for few years now.
And yes, GRUB supports booting into Windows 8.1 / 10.
bji - Thursday, October 22, 2015 - link
They say it because it's true. Nobody wants to have to manage a USB drive just for booting their system. You can also install a floppy drive and boot from that, would you recommend that also? How about keeping a separate computer up constantly to support PXE booting from the network? Would you recommend that level of headache to someone who just wants to boot their frickin computer?bji - Thursday, October 22, 2015 - link
By the way, of all of the things I have to deal with when installing/upgrading Linux systems, grub is the most painful and problematic, by MANY orders of magnitude. I would *NEVER* recommend that a non-technical user have anything to do with grub, especially not for something as silly as booting a PC into Windows off of an NVMe drive.