Question: How long does dd take to copy a 9.1GB disk to another?
Answer: I received about 30 replies - thanks to all for
hints/suggestions/warnings!
General response was that you should never take the default
block size. It
is too small and takes forever to do anything. (5 hours on
the 9GB drive before
I killed it, at the default). Responses said to use
anything from 64K to 1MB for
the block size. Times ranged from 1 1/2 hours to all night.
Below is a response
that may help others...(Thanks Paul)
>From Paul Henderson:
Ah yes, I've dd'd more disks than I care to count, and the key is to
set the blocksize large. dd(1)'s default blocksize is very small... I
don't know the exact number but it is something like 4K. You can
speed things up by specifying a larger block size. I use 399K. For a
4GB disk, this is done is about 15 minutes on a PW433.
Here's the script I use:
#!/bin/csh
#--- clonedisk args: # of disk 1, # of disk 2
echo "copy rz$1 to rz$2? <ret> to proceed"
echo " " <&1
date
echo "copying rz$1 to rz$2..."
disklabel -z /dev/rz$2c
dd -if /dev/rz$1c -of=/dev/rz$2c -bs 399k
echo "done!"
date
Received on Fri May 08 1998 - 23:07:43 NZST