Leading on from my previous question----
Say I wanted to run this backup on a live machine, how do I limit I/O so that the machine remains responsive.
The copy operation itself only uses a small percentage of processor time, but hammers the living daylights out of the disk I/O so surely using nice to limit it wouldn't slow it down much.
It's not important for this particular thing, but I am interested to know if it's even possible considering that the kernel doesn't even really know how busy the disks are.
Or is nice clever enough to know that something else with a higher priority is wanting disk access ?
My plan is that now I have made the initial copy I can use rsync to keep it up to date...or is there a better way ?