[NMLUG] hard drive replacement how to,

[niosop at msn.com (MATTHEW BOWIE)]

While increasing the blocksize might help some, dd is still going to be 
slower than cp when copying a whole device or partion unless the 
device/partition is totally full.  It takes the same amount of time to copy 
a 250GB drive that has 250GB of data on it as it does if the drive only has 
10 meg on it (using dd).

It will also be alot slower to copy from drive to drive if both drives are 
on the same IDE channel.  If possible, put them on seperate channels.

Matthew

>Tim Emerick wrote:
> > Someone noted that dd is very slow.  Probably explains why dd was still
> > cranking away on my 250gig this morning when I woke up.
>
>dd is slow if you use the default option for blocksize, which, IIRC, was
>designed to be backward compatible to magnetic tapes. Try dd if=/dev/hda2
>of=/dev/hdb2 bs=1M (replacing the if= and of= correctly.) If it chokes on 
>that
>argument, try bs=1048576