Re: speed of dd

[Digimer]

On 2021-03-14 7:05 a.m., Ed Greshko wrote:
> On 14/03/2021 18:00, Tim via users wrote:
> > dd if='fedora.iso' of=/dev/sdb status=progress
> >
> > I only get around 6 megabytes per second on a USB 2 Sandisk Cruzer
> > Blade flashdrive (store bought, not fleabay) plugged directly into a
> > motherboard's USB 3 port - one that's not sharing its host with any
> > other ports in use.
>
> Do you get better perfomance if you use a larger block size?
>
> Using USB3 and the default block size I get about 12.6 MB/s
>
> Changing to bs=65536 I get overall 93.5 MB/s on a 2.1 GB iso transfer.

I've gotten into the habit of using bs=4M (matches the extent size of
most LVM backing devices, so md5sum'ing the source and destination is
more reliably useful).