Comment 7 for bug 1310402

I have experienced this also on Ubuntu 16.04.7 LTS when I wanted to move 1,5 TB data to an external USB3 disk.

When I started the mv command it performed well until I have noticed that BackupPC and updatedb.mlocate woke up to do plenty of disk activity, slowing down the source disk of the mv command.
Then I used ionice to set the priority of those processes to "idle" and the mv to "rt/4" priority in the hope that the mv will be able to read at maximum speed while the idle processes will have to wait most of the time until the mv process has finished.

But the performance of the mv process didn't increase as expected.

Both, source and target disks are spinning disks, not SSDs.

I would expect that it should be possible to force the linux kernel to process the mv command to be done in maximum speed while other processes should not be able to steal I/O throughput until the mv is done.
I could have killed the other processes, but this is not what I wanted to do for that.