Samsung SM951 NVMe M.2 PCIe Drive - Low Performance on SSD

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Samsung SM951 NVMe M.2 PCIe Drive - Low Performance on SSD

Postby Apoptosis » Mon Apr 27, 2015 6:58 am

Anyone seen low performance on the Samsung SM951 NVMe drives personally or on another site? I got my hands on a Samsung SM951 NVMe M.2 PCIe SSD and the write performance on it is terrible for some reason. I'm talking sequential write speeds of just 25MB/s and 4K Random writes of under 1MB/s. The sequential read speeds are right where they are supposed to be at 2150MB/s. No matter the benchmark (CrystalDiskMark, ATTO, AS SSD, Anvil or IOMeter) the write performance is always bad.

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samsung-256-anvil.jpg

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The other thing I noticed is that I can't secure erase the drive. The option to perform a secure erase on the Samsung SM951 NVMe doens't show up in Parted Magic or Samsung Magician v4.6 software.

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Then to make matters even stranger the built-in performance test in Samsung Magician v4.6 software shows the Samsung SM951 NVMe drive is hitting 2247 MB/s sequential read and 1440 MB/s sequential write with a 4K Random Read of 173,000 IOPS and a 4K Random Write of 110,000 IOPS. The Samsung SM951 AHCI version has max 4K Random IOPS of 90,000 read and 70,000 write, so the Samsung SM951 NVMe drive is up where we expected it to be. Those numbers sound great, but why won't any other benchmark show that?

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Also, no smart data is shown on the drive. Could a temperature sensor be bad and the drive be throttling due to the sensor error?

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I'm running an ASUS X99 Sabertooth Board with the latest UEFI (v1702) and Windows 8.1 64-bit with all available updates. Samsung doesn't have NVMe drivers, so I am running the Microsoft NVMe drivers that come in Windows 8.1 The drive shows up in the UEFI properly as an NVMe drive. I have tried the ASUS HHHL M.2 add-in card and in the boards integrated M.2 slot and the performance is the same.

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I was just curious if anyone else out there has experienced similar issues and might know of a solution!
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Re: Samsung SM951 NVMe M.2 PCIe Drive - Low Performance on S

Postby hoxlund » Mon Apr 27, 2015 9:25 am

are you using 2 or more video cards? also which slot is your main graphics card in?

just rolling around possible solutions in my head at this point
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Re: Samsung SM951 NVMe M.2 PCIe Drive - Low Performance on S

Postby Apoptosis » Mon Apr 27, 2015 10:23 am

hoxlund wrote:are you using 2 or more video cards? also which slot is your main graphics card in?


The only other PCIe slot that is occupied is the primary PCIe x16 slot and it has an ASUS GeForce GTX 960 STRIX video card in it.
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Re: Samsung SM951 NVMe M.2 PCIe Drive - Low Performance on S

Postby redstorm » Mon Apr 27, 2015 2:28 pm

Apparently Microsofts drivers is issuing a Forced IO command that causes the drive to bypass the DRAM cache and write directly. This of course kills performance. Similar to write through cache policy's on raid controllers.

http://www.sqlskills.com/blogs/glenn/beware-of-the-native-microsoft-nvme-driver/

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Re: Samsung SM951 NVMe M.2 PCIe Drive - Low Performance on S

Postby Apoptosis » Mon Apr 27, 2015 7:40 pm

Samsung got back to me tonight with a somewhat disappointing response:

Our team leader here asked me to make sure that you understand that our OEM customers use their own tools for qualifying and testing NVMe (and other) drives. We do not typically provide to them, so there is nothing that I can send to you for secure erasing the NVMe drive.


So, buyer beware on the SM951 NVMe drives that Samsung does not have any plans to offer any support for this particular drive! No response on the low performance.
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Re: Samsung SM951 NVMe M.2 PCIe Drive - Low Performance on S

Postby Apoptosis » Wed Apr 29, 2015 7:04 am

Something isn't right with CrystalDiskMark 4 Beta 1...

Check out the different numbers in CrystalDiskMark 3.0.4 versus CrystalDiskMark 4 Beta 1 on the same drive (Samsung SM951 NVMe 256GB) run back to back.

cdm-nvme-odd.jpg
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Re: Samsung SM951 NVMe M.2 PCIe Drive - Low Performance on S

Postby larryccf » Fri May 01, 2015 10:21 am

Apoptosis - curious if you can share your source for the NVMe SM951?

and i might be mistaken, but i keep seeing warnings across the various forums not to secure erase the xp941 or sm951 with PartedMagic or samsung's magician utility, one post showing an email response from PartedMagic indicating not to use it's secure erase on the PCIe SSDs

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Re: Samsung SM951 NVMe M.2 PCIe Drive - Low Performance on S

Postby Apoptosis » Tue May 12, 2015 8:07 am

larryccf wrote:Apoptosis - curious if you can share your source for the NVMe SM951?

and i might be mistaken, but i keep seeing warnings across the various forums not to secure erase the xp941 or sm951 with PartedMagic or samsung's magician utility, one post showing an email response from PartedMagic indicating not to use it's secure erase on the PCIe SSDs


I got it from Samsung directly.
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