On Thu, 31 Dec 2009 19:57 +0100, "Tomas Bodzar" <tomas.bodzar@gmail.com> wrote:
quoted text
> I tried it in VM on VirtualBox. Here is my output :
> 
> $ dd if=/dev/rwd0c of=/dev/null bs=1m count=10
> 10+0 records in
> 10+0 records out
> 10485760 bytes transferred in 0.403 secs (25985597 bytes/sec)
> $
> 
> $ dd if=/dev/rwd0c of=/dev/null
> ^C18777+0 records in
> 18777+0 records out
> 9613824 bytes transferred in 8.291 secs (1159492 bytes/sec)
> $
> 
> See difference in speed. So it looks like it's really good idea to use
> bs and count options. 


My earlier suggestion of bs=4m is probably way too large. After 64k, it doesn't get much faster... at least on my USB drives:

# time dd if=/dev/rsd1c of=/dev/null bs=64k 
3859+1 records in
3859+1 records out
252968448 bytes transferred in 23.163 secs (10920945 bytes/sec)
    0m23.16s real     0m0.00s user     0m0.00s system