Ubuntu VM @ 100% CPU (ksoftirq) after scheduled Windows Server Backup jobs RRS feed

  • Question

  • Not sure if this is a Hyper-V or backup issue - trying here first.

    I've had my Ubuntu 10.04 server running happily in a VM on R2 without any issues for a while, but after I scheduled a daily backup job on the host the VM goes to a 100% CPU usage and sits there until it is restarted.

    The process on the VM consuming all the cpu is ksoftirq.

    This doesn't happen every day, but I can see that it start at the exact same time as the backup starts on the host.

    Hardware is Intel Xeon Quad-Core - X3460 on Supermicro X8SIL-F. Windows Server R2.

    The backup job is configured to backup "Bare Metal Recovery" to a dedicated disk and I used one of the instructions found on MS Support (How to back up Hyper-V virtual machines from the parent partition on a Windows Server 2008-based computer by using Windows Server Backup ) to add Hyper-V as an application to be restored individually.

    I'm not sure what the backup software does to the VM when it starts, but appearantly it sometimes put it in a state it can't get out of. I'm at loss where to go next.

     Just adding some more info: Backup is VSS Copy, no errors in the event log, just information event about the sucessful save and then start (floppy, ide, net, scsi) of the VM.

    Tuesday, July 27, 2010 11:10 AM


All replies

  • Looks like a bug in Ubuntu


    ksoftirqd high CPU on 10.04-LTS Server

    1. Ubuntu
    2. “linux” package
    3. Bugs
    4. Bug #575392
    • Marked as answer by Vincent Hu Monday, August 2, 2010 6:19 AM
    Tuesday, July 27, 2010 5:18 PM
  • Hi,


    First of all, Ubuntu is not a supported guest operating system on Hyper-V. For more information, you can refer to:


    Guest Operating System Support



    By the way, it seems that you performed an online backup. As Ubuntu is not a supported operating system on Hyper-V, so you can’t backup it online.


    In addition, you can perform Smjain’s suggestion to see whether you can resolve the issue. You may also wait for other customer's experience sharing on this. Thanks for your understanding.



    Best Regards,

    Vincent Hu


    • Marked as answer by Vincent Hu Monday, August 2, 2010 6:19 AM
    Wednesday, July 28, 2010 5:52 AM
  • Thank you for helping out.


    Yes, I'm aware that Ubuntu is not supported, but since a lot of people are using it I thought it was worth a try :)


    I removed the backup job and perform an offline backup of the VM for now.


    Thanks again.

    Monday, August 2, 2010 7:37 AM
  • Hi!

    I think Xen in the 10.04-Kernel is the problem. Compiling a new Kernel without Xen worked for me:

    apt-get update
    sudo apt-get install fakeroot kernel-wedge build-essential makedumpfile kernel-package libncurses5 libncurses5-dev
    sudo apt-get build-dep --no-install-recommends linux-image-$(uname -r)
    cd /usr/src/
    wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.32.tar.bz2
    tar -xjvf linux-2.6.32.tar.bz2
    cd linux-2.6.32/
    cp -vi /boot/config-`uname -r` .config
    make menuconfig
    => Processor type and features => Paravirtualized guest support => Xen guest support deaktivieren und alles mit Exit verlassen
    export CONCURRENCY_LEVEL=2 (Prozessoranzahl + 1)
    make-kpkg clean
    time fakeroot make-kpkg --initrd --append-to-version=-EIGENER-TEXT kernel-image
    z.B.: time fakeroot make-kpkg --initrd --append-to-version=-ohne-xen kernel-image kernel-headers
    cd ..
    sudo dpkg -i linux-image-2.6.32-ohne-xen_2.6.32-ohne-xen-10.00.Custom_i386.deb
    sudo dpkg -i linux-headers-2.6.32-ohne-xen_2.6.32-ohne-xen-10.00.Custom_i386.deb
    sudo update-initramfs -c -k 2.6.32-ohne-xen
    sudo update-grub


    Now i can suspend and restart the virt. host without a ksoftirqd CPU-Usage at nearly 100%

    Hope this helps somebody (after 2 years) :-)

    Thursday, June 28, 2012 7:55 AM