Why have we hit a wall with 2TB Capacity NVMe SSDs?

Discussion in 'Hardware Components and Aftermarket Upgrades' started by Spartan, Nov 30, 2019.

  1. Casowen

    Casowen Notebook Consultant

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    Oh undoubtedly. Though sas is considered to be more reliable if I recall and is basically a scuzy interface too, which as I recall is the main reason its usually used in enterprise solely. My main gripe about nvme is actually the chip interface which is very inheriantly weak and not durable to shock compared to sata/sas, especially at the connection base.

    Its worth noting that an adapter cable could be ran to the m.2 interface to a u.2 drive in a sata space.
     
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  2. rlk

    rlk Notebook Evangelist

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    Assuming that by "chip interface" you mean the connector, all three of the connectors -- SAS, SATA, and U.2 -- are quite similar. See https://pcper.com/2015/06/the-connector-formerly-known-as-sff-8639-now-called-u-2/.

    SAS implements the SCSI command set (with extensions) over a serial connector. SATA implements the ATA command set over a serial connector. The serial connector is a lot smaller and simpler than the old-style parallel connectors, and doesn't need complex clocking across the parallel bits. SATA does implement a lot more SCSI functionality, but SAS still offers important enterprise functionality that SATA doesn't -- better error recovery and reporting, longer cable length, multiple initiators.

    NVMe, of course, is very tightly coupled to PCIe. That has both advantages -- it's much faster and simpler with lower latency -- and disadvantages -- cable length is much more limited. For the purpose of a laptop, the longer cable length and multiple initiator capability offers no advantage, but the performance very definitely is advantageous.
     
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  3. jaybee83

    jaybee83 Biotech-Doc

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    i was thinking about that when considering a 900P U.2 drive for my machine. problem here is supplied voltage via m.2 is not sufficient to properly power up the drive. not sure if this is a general thing for U.2 drives or specifically related to Optane.

    Sent from my Huawei Mate 20 X EVR-AL00 using Tapatalk
     
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  4. rlk

    rlk Notebook Evangelist

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    Per http://www.ssdformfactor.org/docs/SSD_Form_Factor_Version1_00.pdf U.2 12 volts with 25W max (i. e. a little over 2A) are supplied for M.2, while 3.3 is optional. That seems strange, but there is an implementation note on page 42 (which note looks strange enough too). M.2 is 3.3V, which in principle could be overcome via an active cable, but this person claims that the limit is 7W: https://forums.tomshardware.com/thr...in-power-consumption-among-nvme-ssds.3079717/
     
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  5. jaybee83

    jaybee83 Biotech-Doc

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    yep, im guessing that each laptop vendor would have implemented their own limits. i mean, around 10-12W should already be enough for most if not all "regular" M.2 SSDs, right? :p
     
  6. rlk

    rlk Notebook Evangelist

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    If I'm reading it correctly, M.2 is defined to limit power to 7W, so if your motherboard doesn't at least 7W to the M.2 it's out of spec. Likewise, an M.2 that draws more than 7W is itself not in spec.

    PCIe's slot limit (whatever it is) isn't enough to drive large GPUs and such, so they came up with the auxiliary PCIe power connector. I suppose in principle it would be possible to do the same for M.2, but nobody has done it and there's not a lot of space for such.
     
  7. Vasudev

    Vasudev Notebook Nobel Laureate

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    I think they used custom BGA NAND packages with NVMe 1.3 or higher. I can only link Micron's website and I think Apple used Samsung or Micron or SK Hynix BGA NVMe drives to increase the capacity with small footprint.
    https://www.micron.com/products/nand-flash/3d-nand
    These packages are temperature limited since too much sustained writes or steady state write workloads can heat up not only BGA SSD's but nearby mobo components. And they also make it hard to recover data unless you have specialized tools.
    OR there's a possibility they used 4x 970 pro 2TB drives in BGA form in custom shapes to achieve the feat.
     
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