While copying a vast number of multi-megabyte sound files, the Kubuntu desktop becomes intermittently unresponsive (the mouse pointer can move, but Firefox, Konsole, and KDE itself temporarily ignore keyboard presses, mouse clicks, and network I/O).
$ uname -a Linux jaguar 2.6.32-22-generic #36-Ubuntu SMP Thu Jun 3 19:31:57 UTC 2010 x86_64 GNU/Linux $ cp -Rnv /home/user/music/flac/* .
The PID is 11544, and I subsequently tried:
$ renice -n 19 -p 11544 $ ionice -c 3 -p 11544
Strangely, when remotely accessing a laptop on the local network (via TightVNC), the remote screen continuously updates (if I am using the laptop). Similarly, playing music files off the USB drive (even a file that has not been fully copied) does not get affected by the intermittent unresponsive problem.
Pressing Control-Z to suspend the copy process results in normal behaviour (once the keystroke is finally accepted by Konsole) instantly.
What I was trying to accomplish was the following:
- Rip CDs to desktop (Linux) computer.
- Plug USB drive into laptop.
- Run WinSCP on laptop.
- Copy music files using WinSCP from desktop computer to USB drive on laptop.
However, no matter what software I used (WinSCP, Tunnelier, or rsync over Cygwin), the copy would start at a zippy 2 MB/s, then choke to 60 KB/s after a few seconds. Effectively, the secure copy would stall.
Searches have found a few people who have experienced similar problems. The issues went away for most of them by switching to Tunnelier. This did not work for me. Other people switched to FreeBSD to solve the problem. That's not an option at this time. Still others switched from SSH Protocol 2 to SSH Protocol 1. That did not work for me, either.
The USB drive checked out fine using
chkdsk /f on Windows. There are no relevant error messages in any of the log files from
Monitoring the system using
top shows nothing suspicious when the "pauses" occur. (
top continues to refresh during a moment of unresponsiveness.) The program
hald-addon-storage shows it polls
/dev/sr0 every 2 seconds. Whatever that means.
Quad-core with 8 GB of RAM. The
/tmp drive is empty and
/ shows 72% usage. RAM has 2 GB free and not a single CPU is pegged beyond 1% usage, even during the pauses.
Does anyone have any ideas on what might be happening, or avenues to explore to try and understand what is happening with the system?