dd question

Polytropon freebsd at edvax.de
Sun Sep 27 11:10:47 UTC 2015

On Sat, 26 Sep 2015 19:37:51 -0453.75, William A. Mahaffey III wrote:
> Update: I tried the dd again w/ 'bs=1m' & it worked much faster:

It's a more "native" block size suited for the devices in question.
512 blocks aren't much common anymore. Depending on devicees and
buses, other sizes (like bs=10m) could also achieve higher speeds
for processing.

> The 'ctrl-T' did not in fact return anything, but the 'killall -SIGINFO 
> dd' from another shell window did. 3.4-ish MB/s is quite usable, so all 
> appears well.

Ctrl+T works on FreeBSD's dd, but as far as I remember, not
on Linux's where I had to do the "SIGINFO trick". You should
see something like this:

% dd if=/dev/zero of=/dev/null bs=1m
load: 0.12  cmd: dd 2011 [running] 2.50r 0.01u 2.41s 21% 1944k
19109+0 records in
19109+0 records out
20037238784 bytes transferred in 2.499758 secs (8015671414 bytes/sec)
24797+0 records in
24797+0 records out
26001539072 bytes transferred in 3.239702 secs (8025904599 bytes/sec)

It's the same format as the final status report, prefixed by
some runtime and load information

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

More information about the freebsd-questions mailing list