Sluggish scheduling during a long disk copy

[Dan]

Odhiambo Washington(odhiambo at gmail.com)@2008.11.09 23:25:19 +0300:
> On Sun, Nov 9, 2008 at 11:21 PM, Dan <dan-freebsd-questions at ourbrains.org>wrote:
> 
> > Hello. I am copying one 150G disk to a 3ware mirror, and the machine
> > becomes downright unusable. It takes seconds to switch between 'konsole'
> > windows and it takes seconds between I type a command (ssh session to
> > a remote box, which I know is fast and unloaded) and see it executed.
> >
> > This is 7.1-BETA2. Is this a bug or a generally-accepted performance
> > behavior?
> 
> 
> Bug? :-)
> 
> How are you copying?


I am copying an 'ntfs-3g'-mounted disk to the 3ware mirror with cp -a.
It's around 150G of data, and it's going at about 10MB/s to the mirror.
The mirror uses geom journaling. The speed is fine, the disks are slow.
But should the copy really freeze-up the system like that?