diskinfo -wS truncates [prohibiting slog testing funtime]

[svtkobra7]

Can a kind soul advise why when running diskinfo -wS /dev/nvdx ...
It truncates output @ 256 kbytes: diskinfo: AIO write submit error: Operation not supported
And doesn't continue to 8192 kbytes as per usual?

I have a smorgasboard of different M.2 drives I wanted to bench (this being one quick test I wanted to perform):

• 2x Samsung SSD 970 EVO Plus 500GB
• 2x WD SN750 500 GB
• 2x INTEL SSDPEL1D380GA (905P 380GB)
• 2x P4801x 100GB

Can't wait to mirror 2x INTEL SSDPEL1D380GA (905P 380GB) and throw a P4801x behind it. Should be FUN (for me at least, many here would yawn at such slow speeds).

    diskinfo -wS /dev/nvd3
    /dev/nvd3
    512 # sectorsize
    ...
    Synchronous random writes:
    0.5 kbytes: 42.6 usec/IO = 11.5 Mbytes/s
    1 kbytes: 44.3 usec/IO = 22.0 Mbytes/s
    ....
    128 kbytes: 127.1 usec/IO = 983.6 Mbytes/s
    256 kbytes: diskinfo: AIO write submit error: Operation not supported

[dual post in the interest of transparency on ix too ... surprised it wasn't snagged already - and this is killing me!!!]