Re: external USB disk: 400MB/s transfer, but get only 40MB/s

> On 29 Jan 2026, at 08:59, Matthias Apitz <guru@unixarea.de> wrote:
> 
> # mount_ntfs-3g /dev/da0p1 /mnt
> 
> # dd if=/dev/zero of=/mnt/file bs=8m count=1000
> 1000+0 records in
> 1000+0 records out
> 8388608000 bytes transferred in 183.003888 secs (45.838.414 bytes/sec)
> 
> # dd if=/dev/da0 of=/dev/null bs=8m count=1000
> 1000+0 records in
> 1000+0 records out
> 8388608000 bytes transferred in 67.147415 secs (124.928.234 bytes/sec)
> 


You are writing to an NTFS filesystem and reading a raw disk. That's comparing apples and pears.

Cheers,
	Paul