[Novalug] need dd help

[Paul W. Frields]

Heh, good point.  Thanks for the correction and the chuckle.  I should
try not taking WAGs when caffeine-deprived on a plane.

Paul

On Tue, Feb 14, 2012 at 05:35:52PM +0000, Jason Kohles wrote:
> It wouldn¹t be slower, it would be blazingly fast, since dd would try (and
> presumably fail) to allocate a 1TB chunk of RAM right at startup..  :)
> 
> -- 
> Jason Kohles
> Palantir Technologies | UNIX Systems Engineer
> jkohles at palantir.com  | 703.957.5784
> 
> 
> On 2/14/12 12:23 PM, "Paul W. Frields" <stickster at gmail.com> wrote:
> 
> If you don't have over a terabyte of RAM my bet is that you'd see some
> immense slowdown as dd tries to read input data into memory to fill a
> block before writing it.  But that's a total WAG.
> 
> Paul
> 
> On Tue, Feb 14, 2012 at 09:14:51AM -0500, Ed James wrote:
> > Wonder what upping bs to 1T would do?
> > 
> > Ed James
> > j/k
> > 
> > On 2/14/12, Jay Hart <jhart at kevla.org> wrote:
> > > For the second disk, I up'ed bs from 1k to 1M. Look at the difference:
> > >
> > > [jay at freenas] /dev/ufs# dd if=/dev/zero of=/dev/ada0 bs=1k
> > > dd: /dev/ada0: end of device
> > > 976762585+0 records in
> > > 976762584+0 records out
> > > 1000204886016 bytes transferred in 85322.193527 secs (11722681
> >bytes/sec)
> > >
> > > [jay at freenas] /dev/ufs# dd if=/dev/zero of=/dev/ada1 bs=1M
> > > dd: /dev/ada1: short write on character device
> > > dd: /dev/ada1: end of device
> > > 953870+0 records in
> > > 953869+1 records out
> > > 1000204886016 bytes transferred in 10792.327848 secs (92677400
> >bytes/sec)
> > >
> > > Hugh difference in completion time.
> _______________________________________________
> Novalug mailing list
> Novalug at calypso.tux.org
> http://calypso.tux.org/mailman/listinfo/novalug



-- 
Paul W. Frields                                http://paul.frields.org/
  gpg fingerprint: 3DA6 A0AC 6D58 FEC4 0233  5906 ACDB C937 BD11 3717
  http://redhat.com/   -  -  -  -   http://pfrields.fedorapeople.org/
    The open source story continues to grow: http://opensource.com