On Tue, Aug 14, 2018 at 08:53:08AM -0400, Jerry Geis wrote:

Hello - frequently I turn on my external USB 3.0 disk and back. While my machine is copying and backing up my desktop becomes very sluggish.

Is there a way to change that ? I am using CentOS 7.5 x86 with a very nice processor extra cores available and plenty of memory. There is no reason the "other" cores cannot keep the desktop going.

Are you performing the backup as your user during the same login session? Or is it a separate process/separate login that's doing the backup?

It's possible that the I/O elevator is balancing your backup session with the I/O of the backup, making any disk activity by your login session an equal priority (i.e. competing for resources).

You could always use ionice to make your backup process use idle resources.