Samsung SM951 512GB M.2 PCIe SSDs in RAID 0 – Hitting 4.5GB/s

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Samsung SM951 M.2 PCIe SSDs in RAID 0

Samsung SM951 RAID

If our review yesterday on the Samsung SM951 512GB M.2 PCIe SSD was interesting to you, but found yourself thinking that the first M.2 PCI Express 3.0 x4 storage drive just isn’t fast enough for you we have a treat for you today. We managed to get our hands on another Samsung SM951 512GB Drive (part number MZ-HPV512) and slapped it on our Intel X99 desktop test system to make a dynamic RAID 0 array! A single Samsung SM951 512GB M.2 PCIe SSD is capable of 2150MB/s sequential read and 1500 MB/s sequential write speeds, so this setup could possibly get us up to 4300 MB/s sequential read and 3000 MB/s sequential write if all works as planned since we’d be running the SSDs in tandem. With speeds like that your programs should open damn near instantly and moving around your cache of movies should take just seconds instead of many minutes.  If you are looking for blindingly fast SSD speeds that will make you drool and open your wallet you don’t want to miss out on these results as we ended up with the fastest 2-drive RAID 0 setup that we have ever made!

Samsung SM951 M.2 PCIe SSD Drive Specifications
Part Number Capacity and Features Sequential (R/W) Max 4K IOPS QD4 (R/W) Price
MZ-HPV2560 M.2 2280 Form Factor 256GB 2150/1200 MB/s 90k/70k IOPS $264.95
MZ-HPV5120 M.2 2280 Form Factor 512GB 2150/1500 MB/s 90k/70K IOPS $499.95

The Samsung SM951 M.2 SSD is available in 256 and 512GB capacities and are priced at $1.04 and $0.98 per GB, respectively. These high-end Samsung SM951 M.2 drivers are the first M.2 PCIe 3.0 x4 drives to come to market, so to pay around a buck per GB to be on the bleeding edge of SSD technology isn’t really absurd. The Samsung SM951 should be of interest to power users that are looking for a drive that can handle the data throughput needed to edit 1080P and 4K video or any other SSD bottlenecked task that one can think of.

Samsung UBX Controller - ARM

The Samsung SM951 512GB M.2 SSD series uses the Samsung SLN058A01-8030 UBX controller, which just happens to be the first PCIe 3.0 x4 SSD Controller that has come market. The UBX controller supports four Gen 3.0 PCIe lanes, which is theoretically good for 4GB/s of bandwidth. We have been told that the PCIe bus is only about 80% efficient, so realistically you are looking at 3.2GB/s for being the realistic maximum bandwidth of the interface, which is still well below the maximum rated 2.15GB/s sequential read speed of the SM951. The controller is linked to a 512GB DDR3 memory chip for drive caching purposes.

Samsung SM951 RAID 0

If you want to run a pair of M.2 PCIe SSDs in RAID you’ll either need to have a board that has enough slots for a couple drives or you can use half-height, half-length (HHHL) adapters to get the job done. Since current chipsets fail to support M.2 PCIe RAID setups, we’ll need to setup a dynamic RAID array in Windows for our RAID0 array. Starting with Microsoft 2000 there is built-in functionality to set up a software RAID without any additional tools, but the dynamic volume will not be bootable. If you wanted a bootable RAID setup you’d have to invest in a hardware RAID card and we don’t know of one yet that will work for M.2 SSDs.  Setting up a dynamic RAID array in Windows 8.1 is painless, so we’ll walk you though the process.

In order to do create a dynamic RAID array you’ll need to open Windows Disk Management remove any volumes on the two disks if they were previously used and then just right click one and pick the type of RAID volume that you want to set up dynamically. For RAID 0 you’ll need to create a stripped array, assign a drive letter and name it. After following a handful of simple prompts you’ll end up with a striped dynamic RAID array and . You can click through the screen captures above to see the steps that are needed once you get into Windows Disk Management.

Let’s take a look at the test system and see how fast the Samsung SM951 M.2 PCIe SSD RAID 0 setup is!

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  • Wil70

    I setup some very fast PCIe SSD as Virtual memory on windows and the performance are the same as with a HDD, why? any way to improve it? (I have a custom app that use a lot of memory, more than my system has, so I put some fast PCIe ssd hoping to see a little more improvement at least when it access the disk, big deception, this is the same performance as with a hdd)

  • KB Grand

    Update: With the introduction of Intel Skylake / Z170 a Raid 0 configuration is possible with PCIe 3.0 using M.2s.

    I came across this link:

  • Dan the man

    Currently £126 at for the 256GB have one in my z97 board with an pcie adapter card as the m.2 slot is only x2

  • xyvyx

    It might be awhile before we have a hardware controller that can handle PCIe storage. Storage Spaces shows near RAID0 read performance with a mirrored configuration, but both SS & conventional windows mirroring still has this strange bottleneck, at least visible via ATTO.

    I can run the test simultaneously between 2 or even all 4 drives and they can all independantly test out at > 2,500 MB/sec, but when combined with any form of software RAID, something is farbled up 🙁 But in theory, yeah, we should be able to hit 8 GB/sec with 4 of these drives. Which is pretty insane 🙂


      So with CrystalDiskMark and 4 drive are you able to achienve 8GB/s? If I read correctly the mdsn link you put the guy at msft was able to achieve 10GB/s correct?, it seems the problem come from ATTO?
      Can you do a raid with them without using storage space? (I saw some limitation with storage space, like not being able to use it as paging disk )for virtual memory)
      I have a MSI x99 SLI plus, I’m hesitating with 3x intel 750 PCie NVMe or 3x Samsung sm951, do you have any advise? I need a lot of reading speed – thanks.

      • xyvyx

        Yes.. better, but only with “ideal” number of threads and queue depth… I specified Q8T48 in Crystal and got the results shown on here:

        note that I only used the default 1GiB test file there… but this doesn’t have the same sort of cache as a raid controller, so the results here should’t be skewed so much.

        I did regular windows software raid and it works, but you only get the read performance equivalent of a single drive. The Storage Spaces in server 2012 and Windows 8 is smart enough to read from both disks, although write performance is limited to (# of drives) / 2. That was my post on the the Microsoft forum, and yeah, I got over 10GB/sec with SQLIO. I think with SS, you’d be unable to boot off the volume either.. not sure if that’s a concern.

        I’ve got a single SM951 in my system here @ home.. it’s wicked fast. I think the Samsung’s might be a better choice for you in terms of pure read speed unless your application will be very multi-threaded, where the Intel would pull ahead. So it sorta depends what you’re doing.

        I’ve done some basic tests with a SQL database.. on the old server, a quad-socket xeon (32 cores total) w/ the data file on a 16-disk RAID10 array (15k rpm sas), one of my test queries takes 12 seconds. On the SSD array, it takes 1 second.

        • Wil70

          Hello xyvyx, I setup some very fast PCIe SSD as Virtual memory on windows 8.1 and the performance are the same as with a HDD, why? any way to improve it? (I have a custom app that use a lot of memory, more than my system has, so I put some fast PCIe ssd hoping to see a little more improvement at least when it access the disk, big deception, this is the same performance as with a hdd, the throughput of the ssd is really bad when used by the Virtual memory, it is really good if I use it as normal drive)

        • xyvyx

          (sorry for the late reply)

          I suspect that if the performance didn’t change when moving the swap file to a SSD that the bottleneck with your app wasn’t the swap file in the first place.

          Use perfmon & see how the disks are behaving. ie: Physical Disk – avg queue length bytes tranfer, etc… queue length should be very low/zero on your SSD unless you’re doing a lot of parallel reads/writes.

          When you say “some”, do you mean multiple SSDs? or just one?

          In the case of my server tests, ATTO had a bottleneck with throughput where other apps and benchmarks did not. Granted, that bottleneck was pretty high, but it was like a brick wall. Actually, it was worse.. when the number of IO requests went above some threshold, overall throughput dropped. So maybe your app is doing something similar… it’s requesting data from the disk in a certain combination of size, queue & threads that’s making things worse.

  • wil70

    Can you do a hardware raid 0 (with the motherboard or other controller)? will this be faster?

  • wil70

    can you do a raid with 3 or 4 pcie ssd? If I put 4 of these will this approach to the speed of the RAM?

  • xyvyx

    wow, looks like you’re running into some of the same bottlenecks I am with the ATTO benchmarks! I’ve got a Dell server with several of their NVMe Expressflash drives. I thought my problem was with the Server 2012 Storage Spaces, but I just did an old-school striped pair w/ windows disk manager and saw the same thing… after ~ 4,200 MB/sec, the read performance takes a nosedive.

    I have 4 of the devices, all with a 4x PCIe interface connected to a 16x backplane. I’ve tried them in different combinations and using all 4 in a single 2-column, 1 copy storage pool… it doesn’t matter.

    Other benchmarks might show it as being plenty fast, but I’ll be using this as a SQL server, so I know it’ll be making large sequential reads and I don’t want this issue to be a bottleneck 🙁

    I put some of my graphs on Technet here:

  • BenSer90

    Nice review! I have learned this Samsung
    SSD could be really useful, just like my Samsung external hard drive that works
    fine with small size and fast speed. But, I had never tried this SSD and don’t
    know whether it could be practical in actual use. Hope it is not bad for real
    life setup.

  • jt AJ

    btw, the ATTO having problems at larger block size with changing qdepth is probably caused by formatting size. try changing format size to 64kb instead of window default 4kb that maybe fix the issue up till a certain of qdepth.

    also kind of pointless to do video editing on two raid devices simply because they video edit runs at 6-10 qdepth which as we can see drives got problem.

    another is with window software raid, latency increases and it defeats purposes of having just fast sequential unless running games and only games. we’ll all probably wait until intel releases nvme raid 0 capable bootable before buying two in raid.

  • Magatama

    LOL, the performance didn’t drop off on ATTO reads, it overflowed an unsigned 32bit int (4294967296) it was so fast!

  • guest nonstop

    useless in real life setup. Runs very hot, needs fan.

    • Double460

      I have 4 Kingston HyperX 240Gb in raid 0 with a LSI-9260 controller and they go up to a sizzling 30C with 100% full load… and I have same speeds as in this article… now where could I find some nice fans for this… not to mention a state of the art thermal paste.