On 07/09/2014 08:00 PM, Greg Freemyer wrote:
On Fri, Jul 4, 2014 at 8:43 PM, David C. Rankin
What about using ibs=512 obs=4096? Will that cause the desired 512 read and 4096 write, or will there be alignment issues attempting to copy from 512 and write 4096? And as Berny suggested could iflags or oflags set to fullblock help?
I just ran across this post again. No, using ibs / obs with dd will not help the long term efficiency of the partitions / filesystems at all.
When copying partitions or whole disks, I usually use larger buffers like bs=128M or bs=1G. The problem arises if one of the physical input blocks is corrupt, then the whole output block might be padded with Zeros. That's why ddrescue (or dd_rescue) are more specialized in such a failing disk case: they copy with adaptive block sizes, trying to rescue as much data as possible around the failing blocks. For healthy disks, dd(1) perfectly fits my needs though. Have a nice day, Berny -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org