@brummyfan2, why the sequential read and write of NVMe are less than 50% of the SATA? i'm a newbie.

joeralds
joeralds Member Posts: 3 New User
edited November 2023 in 2020 Archives
   

Best Answers

  • aphanic
    aphanic Member Posts: 959 Seasoned Specialist WiFi Icon
    edited August 2020 Answer ✓
    I don't know if mentions on the title work... maybe you should have called him in the body as well but I'll summon him for you, @brummyfan2.

    Although, regarding the data you show, I am fairly sure the answer has to do with 2 things:
    1. There are only 2 PCIe lanes wired to the M.2 slot in your machine, I don't know which one it is be seeing that secuencial reads and writes on the NVMe drive never get past the 2000MB/s mark it seems plausible. You can think that each lane gets you up to 1000 MB/s.
    2. RAPID is enabled for the SATA drive, there's no other way around it haha. RAPID is a mode in which part of the RAM is used as a cache for the disk, to speed things up. That 860 EVO being a SATA III drive would never get past 6 Gbps, ~768 MB/s without accounting for losses because those are the limits of that interface.
    I think the setting for RAPID was in "Performance Optimization" but I don't quite recall.
  • aphanic
    aphanic Member Posts: 959 Seasoned Specialist WiFi Icon
    Answer ✓
    joeralds said:
    @aphanic, thank you so much! so it's better to use the 860 EVO as system drive with RAPID mode on than NVMe? because NVMe does not support RAPID mode.

    Maybe... I have never seen myself in that situation haha, either I had machines that had no option for M.2 drives, or I had machines with M.2 drives and didn't need RAPID or wasn't supported because the drive I had installed wasn't Samsung branded.

    I think I'll use the M.2 drive for the OS anyway though, those speeds are pretty good and the others depend on the size of the cache in RAM of which we know nothing or very little about. Maybe the test they're doing in that screen is just using so little data that it fits the cache and you see the SATA drive being faster, but think that when the cache is full or it needs to be flushed to disk those speeds will go down while the speeds you see in the M.2 drive are stable, they'd always be the same.

Answers

  • aphanic
    aphanic Member Posts: 959 Seasoned Specialist WiFi Icon
    edited August 2020 Answer ✓
    I don't know if mentions on the title work... maybe you should have called him in the body as well but I'll summon him for you, @brummyfan2.

    Although, regarding the data you show, I am fairly sure the answer has to do with 2 things:
    1. There are only 2 PCIe lanes wired to the M.2 slot in your machine, I don't know which one it is be seeing that secuencial reads and writes on the NVMe drive never get past the 2000MB/s mark it seems plausible. You can think that each lane gets you up to 1000 MB/s.
    2. RAPID is enabled for the SATA drive, there's no other way around it haha. RAPID is a mode in which part of the RAM is used as a cache for the disk, to speed things up. That 860 EVO being a SATA III drive would never get past 6 Gbps, ~768 MB/s without accounting for losses because those are the limits of that interface.
    I think the setting for RAPID was in "Performance Optimization" but I don't quite recall.
  • joeralds
    joeralds Member Posts: 3 New User
    @aphanic, thank you so much! so it's better to use the 860 EVO as system drive with RAPID mode on than NVMe? because NVMe does not support RAPID mode.
  • aphanic
    aphanic Member Posts: 959 Seasoned Specialist WiFi Icon
    Answer ✓
    joeralds said:
    @aphanic, thank you so much! so it's better to use the 860 EVO as system drive with RAPID mode on than NVMe? because NVMe does not support RAPID mode.

    Maybe... I have never seen myself in that situation haha, either I had machines that had no option for M.2 drives, or I had machines with M.2 drives and didn't need RAPID or wasn't supported because the drive I had installed wasn't Samsung branded.

    I think I'll use the M.2 drive for the OS anyway though, those speeds are pretty good and the others depend on the size of the cache in RAM of which we know nothing or very little about. Maybe the test they're doing in that screen is just using so little data that it fits the cache and you see the SATA drive being faster, but think that when the cache is full or it needs to be flushed to disk those speeds will go down while the speeds you see in the M.2 drive are stable, they'd always be the same.
  • joeralds
    joeralds Member Posts: 3 New User
    @aphanic, thank you so much. so i will stick to M.2 as OS drive.