MP 7,1 nCMP SSD - How Slow?

Discussion in 'Mac Pro' started by Slash-2CPU, Jun 11, 2019 at 9:55 PM.

  1. Slash-2CPU macrumors regular

    Joined:
    Dec 14, 2016
    Location:
    New Orleans, USA
    #1
    Apple has it as “up to 2.6GB/s sequential read and 2.7GB/s sequential write.”

    That’s slower than a 970 PRO or EVO. I’d love to know the 4K IOPS at low queue depths.

    Thinking maybe get the 256GB option and never use it. Drop in Samsung’s and maybe even an Intel 905p for working drive.

    Anyone have thoughts on this? I’m sure the 256GB -> 1TB option will cost more than a 1TB 970 EVO.
     
  2. dfgddikf macrumors regular

    Joined:
    Sep 10, 2015
    #2
    You won't be able to drop in aftermarket SSDs. Apple is using proprietary SSDs.
     
  3. Slash-2CPU thread starter macrumors regular

    Joined:
    Dec 14, 2016
    Location:
    New Orleans, USA
    #3
    Really? So I can’t use a single, dual or quad m.2 to PCIe adapter I guess? If only the nCMP had PCIe slots. The 905p I mentioned is a PCIe x4 AIC.

    I see the onboard SSD’s as a total non-starter dead end. Proprietary interface, high $/GB and, relative to the rest of the machine, slow.
     
  4. G4DPII macrumors regular

    G4DPII

    Joined:
    Jun 8, 2015
    #4
    Will all depend on what the T2 chip will and will not allow.
     
  5. Slash-2CPU thread starter macrumors regular

    Joined:
    Dec 14, 2016
    Location:
    New Orleans, USA
    #5
    I expect it will be the same as it is now with the startup security settings to allow booting from other devices.
     
  6. shokunin macrumors regular

    Joined:
    Jun 7, 2005
    #6
    When they flashed the images of PCIe cards during the Keynote, the one on the far left was Sonnet Tech's m.2 4x4 PCIe card. x16 lane PCIe card with 4 m.2 nvme slots. Just boot off the 256gb and add your own supplmental storage. Put all your apps and files on the PCIe card.

    The t2 chip isn't likely to prevent you from using another storage device. It hasn't prevented macbook pros from using an external PCIe thunderbolt drive.
     
  7. chfilm macrumors 68000

    chfilm

    Joined:
    Nov 15, 2012
    Location:
    Germany
  8. thornslack macrumors 6502

    Joined:
    Nov 16, 2013
    #8
    But can you make a pcie volume bootable with the t2?
     
  9. tsialex macrumors 601

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #9
  10. Slash-2CPU thread starter macrumors regular

    Joined:
    Dec 14, 2016
    Location:
    New Orleans, USA
    #10
    A relatively cheap m.2 SSD can outperform that by 10-20%. For all the CPU cores, insane GPU power, and massive RAM bandwidth, the SSD is slow. It’s like having bicycle wheels on a Formula car.

    My primary work use is extremely disk intensive and all low queue depth small random. About 80-90% read and 10-20% write. It loves RAM bandwidth and seems to scale ok to 12 cores. I expect that with the 12-core and 6x8GB I will be severely disk-bound. That’s why I’m looking at the Optane 905p for a working disk.

    Then I started thinking those specs are slower than the m.2 SSD on a dual m.2 adapter in my cMP. That’s kind of absurd.
     
  11. tsialex macrumors 601

    tsialex

    Joined:
    Jun 13, 2016
    Location:
    Brazil
    #11
    I'm not defending Apple here, Apple SSD prices are absurd, but this is more nuanced since most M.2 PCIe SSDs have a high initial throughput when everything is on the cache, then a substantial drop with write tests after the SLC buffer is full, this is very pronounced with drives/blades that use QLC NAND. iMac Pro tests show that Apple SSDs don't have this problem since Apple usually uses the best SLC and MLC NAND available.

    There is another problem with cell write exhaustion in the long run too, SLC and MLC drives/blades are a lot less susceptible to it than the cheap M.2 blades with QLC NAND. It's not so simple to analyse this.
     
  12. Slash-2CPU thread starter macrumors regular

    Joined:
    Dec 14, 2016
    Location:
    New Orleans, USA
    #12
    True. We’ll know more when first tests and reviews are out. No telling yet on long-duration writes or mixed read write performance. I’ll be very surprised if it outperforms 970 Pro with a heatsink in either random or sequential sustained writes. I’ll be absolutely shocked if it beats Optane 905p in long duration low queue depth mixed read write, which is my main interest.

    I could keep all the data in RAM and never use the SSD, but I’d have to sell my car to afford the RAM. Lol.
     
  13. ZombiePhysicist macrumors 6502a

    ZombiePhysicist

    Joined:
    May 22, 2014
    #13
    Seems to me the way to go is to get a NVMe PCI card and a fast NVMe drive and just boot off that. The apple SSD connection is just crap.
     

Share This Page

12 June 11, 2019