In the meantime I know that on the system where I suspected the issue to
exist the I/O had a lot of issues unrelated to `garted`. It does no
longer exist, but there seems to be no problem while copying with the
tested block sizes after all. Thanks for your input.
** Changed in: gparted (Ubuntu)
Generally speaking, the block size makes very little difference anyhow
so I think that is a red herring. Can you provide more information
about this move? What kind of filesystem? From where to where was it
moved? Can you run dd if=/dev/zero bs=1MiB
of=/path/to/some/file/on/this/drive count=512
