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I copied a 16 GB USB memory stick to another 16 GB stick (cloned it), by using the following command:

cp /dev/sdb /dev/sdd

It took about 27 minutes, and the cloning works. But during the entire copy process, the mouse and cursor movement become erratic, and lag terribly. This makes using the laptop during the copy almost impossible.

This happened to me on a previous occasion, so the effect is reproduci ble.

What causes this effect?
How do I stop the erratic behaviour?
Are you able to replicate the behaviour on your computer?

Artem S. Tashkinov
  • 29,025
dave99
  • 1

1 Answers1

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What causes this effect?

Probably SWAP use and dirty buffers coupled with most likely slow storage (i.e. HDD). More on it here: https://lwn.net/Articles/572911/

How do I stop the erratic behaviour

Disable swap altogether + cat /etc/sysctl.d/vm.conf + use a newer kernel. If you're running something like Debian 9 or CentOS 7, your kernel could have this issue.

vm.dirty_background_bytes = 33554432
vm.dirty_bytes = 134217728

Are you able to replicate the behaviour on your computer?

No, I have this workaround, SSD, SWAP is disabled and 64GB of RAM.

Also check this topic:

Artem S. Tashkinov
  • 29,025