Troubleshoot VM problems

Citrix provides two forms of support:

  • Free, self-help support on the Citrix website
  • Paid-for Support Services, which you can purchase from the Support Site.

With Citrix Technical Support, you can open a Support Case online or contact the support center by phone if you experience technical difficulties.

The Citrix Support site hosts several resources that might be helpful to you if you experience unusual behavior, crashes, or other problems. Resources include: Support Forums, Knowledge Base articles, and product documentation.

If you see unusual VM behavior, this section aims to help you solve the problem. This section describes where application logs are located and other information that can help your XenServer Solution Provider and Citrix track and resolve the issue.

Important:

Follow the troubleshooting information in this section only under the guidance of your XenServer Solution Provider or Citrix Support.

Vendor Updates: Keep your VMs up-to-date with operating system vendor-supplied updates. The vendor might have provided fixes for VM crashed and other failures.

VM crashes

If you are experiencing VM crashes, it is possible that a kernel crash dump can help identify the problem. Reproduce the crash, if possible, and follow this procedure. Consult your guest OS vendor for further investigation on this issue.

Control Linux VM crashdump behavior

For Linux VMs, the crashdump behavior can be controlled through the actions-after-crash parameter. The following are the possible values:

Value Description
preserve Leave the VM in a paused state. (For analysis)
restart No core dump, just reboot VM. (This is the default)
destroy No core dump, leave VM halted.

To enable saving of Linux VM crash dumps:

  1. On the XenServer host, determine the UUID of the desired VM by running the following command:

    xe vm-list name-label=name params=uuid --minimal
    
  2. Change the actions-after-crash value using xe vm-param-set; for example, run the following command on dom0:

    xe vm-param-set uuid=vm_uuid actions-after-crash=preserve
    
  3. Crash the VM.

    • For PV guests, run the following command on the VM:

       echo c | sudo tee /proc/sysrq-trigger
      
    • For HVM guests, run the following command on dom0:

       /usr/lib/xen/bin/crash_guest vm-domid
      
  4. Execute the dump core on dom0. For example, run:

    xl dump-core domid filename
    

Control Windows VM crashdump behavior

For Windows VMs, the actions-after-crash parameter cannot control the core dump behavior. By default Windows crash dumps are put into %SystemRoot%\Minidump in the Windows VM itself.

You can configure the VMs dump level by following the menu path My Computer > Properties > Advanced > Startup and Recovery.

Troubleshoot boot problems on Linux VMs

There is a utility script named xe-edit-bootloader in the XenServer host control domain. This script can be used to edit the bootloader configuration of a shutdown Linux VM and fix problems that prevent the VM from booting.

To use this script:

  1. Run the following command:

    xe vm-list
    

    This command ensures that the VM in question is shut down (the value of power-state is halted).

  2. You can use the UUID as follows:

    xe-edit-bootloader -u linux_vm_uuid -p partition_number
    

    Or, you can use the name-label as follows:

    xe-edit-bootloader -n linux_vm_name_label -p partition_number
    

    The partition number represents the slice of the disk which has the filesystem. For the default Debian template, the partition number is 1 since it is the first partition.

  3. You are dropped into an editor with the grub.conf file for the specified VM loaded. Change the file to fix it, and save the file, exit the editor, and start the VM.

Troubleshoot VM problems