On 20090110T2323, "Butler, Jeff" wrote: > > Examples, with "if=/dev/sda of=/dev/sdb" omitted for brevity: > > - 750 GB: dd bs=8192 count=91571823 takes 07h12m > > - 535 GB: dd bs=1440256 count=371567 skip=149282 seek=43831 takes > > 07h08m > > First, as you move to the inner tracks of a disk, performance will drop. > That's what seek/skip will cause to happen. Disks will vary, but it > would not surprise me to see the bandwidth drop in half when you move to > the inner tracks.
Thanks for your answer. I think, however, that this is not what's happening. The first command encompasses the second one, both on the source disc and on the target disc. That is, the first command /reads/ all sectors that are also read in the second command, and then some more. Same for the target disc: the first command /writes/ all sectors that are also written in the second command, and then some more. I therefore expect the first command to take significantly more time than the second one, as it has almost half as many sectors to transfer. Rotaluclac
