WD black SN850X - write cmd - constrained to 8MB size only

Internal Drives WD_BLACK
1

Hello

I am using the WD black and we are developing a special driver for it for FPGA devices
we see that the NVME cannot perform Write operation with more than 16 LBA = 8MB

  • Seems that its limited by configuration . is it correct ?
  • if its the case , any idea how to change this configuration ? can it be done on windows machine ? can it be done in linux machine ? if yes how ?

Thx
Kikoss

2

Disks and SSD alike a block oriented. I use Windows which can read any block and it can read as many blocks as needed.

I use C and C++ and KERNEL32 for low level disk access.

3

yes i agree that we can write as many block as we need , iam asking per write command its limited to 16 block . do you see such constraint on your low level C/C++ access ?

4

Today C and C++ use Win32 so read and write to files and files are more abstract than blocks. Wirth TB of disks file based API is all that is needed anymore.

CHKDSK can fix disk problems fairly quick but the /R option scans the media for errors

5

The 16 LBA (8MB) write limit on your WD Black NVMe SSD is likely due to firmware constraints, NVMe driver settings, or OS behavior.

Key Points:

  • Possible Causes: Firmware limitations, NVMe driver restrictions, or OS-level constraints.
  • Checking the Limit:
    • Windows: Use nvme-cli in WSL or low-level Windows APIs.
    • Linux: Run nvme id-ctrl /dev/nvme0 or check max_hw_sectors_kb.
  • Can It Be Changed?
    • Some SSDs allow modification via vendor-specific NVMe commands or firmware updates, but user access is limited.
    • For FPGA use, direct interaction with the NVMe controller via PCIe registers may be required.