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NVMe 2.0 Brings Support for PCIe-Connected Hard Disk Drives

Hard drives
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The new NVM Express 2.0 (NVMe 2.0) Protocol has been released. While the thrust of the protocol focuses on flash storage and networking, the latest additions include full-blown support for hard disk drives (HDDs).

The addition of hard drive support is one of the biggest changes coming to NVMe 2.0 and something most people will be surprised to see, as current 7200-RPM hard drives cannot fully saturate current SATA 3.0 connections. However, like other forms of tech, hard drives are evolving, which might eventually require a bandwidth upgrade beyond SATA 3.0 speeds. For instance, Seagate announced two weeks ago that it's Mach.2 hard drives can reach up to 524MB/s, a speed previously only capable with SSDs.

Drives like the Mach.2 could become very popular over the next few years, as hard drive capacity escalates beyond 20TB to fulfill the needs of the enterprise and data center world. Drives like these will need significantly higher bandwidth to ensure that accessing more than 20TB of data won't take long.

However, simplifying the ecosystem down to one storage connection seems to be the main impetus for adding hard drive support, particularly as the NVMe spec continues to evolve its NVMeoF (NVME over Fabrics) functionally that allows the drives to be networked without additional abstraction layers.

NVMe 2.0 hard drive support could also signal the beginning of a decline of the SATA protocol as a whole since the protocol has not been updated in over 12 years. Getting rid of SATA and migrating all hard drives to NVMe could free up some space on motherboards and simplify storage connections (at least in the consumer space) to just NVMe, but don't expect that change to happen any time soon – the latest word in the storage industry is that it will take a few more years before we see NVMe HDDs ship in high volumes. 

Here's the rest of the NVMe 2.0 feature set. Overall, these features aim to reduce NVMe's overhead and give your PC more control over your SSD.

  • Zoned Namespaces (ZNS) is coming to NVMe 2.0 and will allow the SSD and host to collaborate data placement within the drive itself. ZNS will permit data to be aligned to the physical media of the SSD which will improve overall system performance and give your PC more of the SSD's storage capacity.
  • NVMe Key-Value Command Set will provide access to data on an NVMe SSD namespace using a key instead of a logical block address. Switching from logical blocks to keys will reduce overhead by not having the SSD maintain a translation table for the logical block address.
  • Rotational media support is the name for Hard Disk Drive support for NVM Express. This will include new updates to features and enhancements required for HDD support.
  • NVMe Endurance Group Management will enable media to be configured into Endurance Groups and NVM Sets. This exposes granularity of access to the SSD and improved control.
  • NVMe 2.0 will be backward compatible with previous NVMe architecture generations. Allowing future NVMe 2.0 SSDs to work with current M.2 capable motherboards and M.2 cards.
  • hotaru.hino
    Having everything on one protocol sounds nice, but then I ask how will this all be connected?
    Reply
  • JarredWaltonGPU
    hotaru.hino said:
    Having everything on one protocol sounds nice, but then I ask how will this all be connected?
    Yeah, no doubt. Will we use U.2 cables for all our devices? And I guess we'll have to have shared PCIe lanes if we're going to have more than a few U.2 / M.2 / whatever ports.
    Reply
  • kal326
    WD mentioned this last year about SMR hard drives support in ZNS. Makes sense given the sequential write performance in large block SMR drives versus random write operations.
    Reply
  • dehjomz
    A few questions:
    What connector will be used to attach hard drives to pcie via the nvme protocol?
    Does this mean we may finally see a samsung evo 870 successor that eschews sata and uses pcie instead, and runs much faster than 550MB/sec?
    What's the theoretical maximum speed of a pcie hard drive?
    Are we potentially talking pcie5.0 bandwidth in a 2.5 inch hard drive form factor?
    Reply
  • hotaru.hino
    dehjomz said:
    What connector will be used to attach hard drives to pcie via the nvme protocol?
    Does this mean we may finally see a samsung evo 870 successor that eschews sata and uses pcie instead, and runs much faster than 550MB/sec?
    What's the theoretical maximum speed of a pcie hard drive?
    Are we potentially talking pcie5.0 bandwidth in a 2.5 inch hard drive form factor?
    The only NVMe based connector that I'm aware of for use with traditional storage drives is U.2
    That would be the 970.
    No faster than what the fastest hard drive on the market is. Hard drives haven't even saturated SATA 3 yet.
    Maybe available to it, but no hard drive is going to reach those speeds.
    Reply
  • mikewinddale
    And now SATA Express feels even more rejected. (For those who don't remember, the SATA Express connector was backwards compatible with SATA and the AHCI protocol but it also included two lanes of PCIe and the NVMe protocol.)
    Reply
  • USAFRet
    dehjomz said:
    Are we potentially talking pcie5.0 bandwidth in a 2.5 inch hard drive form factor?
    Not a chance.
    Mechanical drives are still mechanical.

    They can't even saturate a SATA II connection.
    Reply
  • InvalidError
    USAFRet said:
    Not a chance.
    Mechanical drives are still mechanical.

    They can't even saturate a SATA II connection.
    As pointed out in the article, Seagate's fastest SATA HDDs can max SATA III out using dual actuators. Bandwidth could hypothetically increase further with triple and quad actuators in the future. My 7 years old WD Black peaks at 240MB/s sequential, so SATA II was already quite close to being a bottleneck for fast HDDs back then.

    Even SATA3 is becoming inadequate for today's fastest HDDs.
    Reply
  • TommyTwoTone66
    hotaru.hino said:
    Having everything on one protocol sounds nice, but then I ask how will this all be connected?

    These will be for servers. There will be PCIe connectors inside NAS enclosures, large-scale SAN devices or storage arrays inside giant server racks.

    Consumer grade stuff will continue to be solid state drives in NVMe slots.
    Reply
  • InvalidError
    TommyTwoTone66 said:
    Consumer grade stuff will continue to be solid state drives in NVMe slots.
    I'd imagine that dual-actuator HDDs able to push SATA3 beyond its limits will get into the upper-end of mainstream for people who want 8+TB of storage or have a NAS. If you can get multi-actuator HDDs with 2-4X the throughput, you can rebuild a compromised RAID array 2-4X as fast.
    Reply