"da0: 40.000MB/s transfers" What was rationale behind pegging USB 2.0 at 40MB/s?

Wojciech Puchar wojtek at wojtek.tensor.gdynia.pl
Mon Jul 23 07:40:23 UTC 2012

> dd if=/dev/zero of=/dev/da0 bs=1 to 15M
> runs, 13-14MB/s from actual files copied
> in mc to flash and 36-39MB/s file copied
> from flash to hdd in mc.
> dd if=/dev/da0 of=/dev/zero bs=15m
> gives 33MB/s read.
and this is incredibly high as of any pendrive.

Consider few things:

- pendrive flash mappers are incredibly dumb, they work in usable speed 
when you do linear write only.

- today lies are standard. never believe in stated performance unless you 
measure it.

> even recognized in FreeBSD as device.
what i do with any pendrive:

dd if=/dev/zero of=/dev/da0 bs=64k count=1
newfs_msdosfs /dev/da0 (if i want FAT filesystem)

partition table is not needed in any OS, including Windows starting from 

msdosfs in FreeBSD isn't high performance too.

try writing small amount of huge files.

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