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XEN: Howto migrate loopback file based disk images to blktap tap:aio

This document (7000716) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 10 Service Pack 2

Situation

Migrate a loopback file based disk image to a blktap tap:aio disk image without reinstalling the DomU.

Resolution

  1. Backup current DomU configuration:
    xm list <DomU_ID> -l > /tmp/vm1.conf
  2. Edit disk device section of the configuration file:
    vi /tmp/vm1.conf

    # Configuration example

    (device
    (vbd
    (unamefile:/xen/vm1/disk0)
    (uuid d2cb4a14-ecbd-6034-3d4c-7866bfd4b60e)
    (mode w)
    (devxvda:disk)
    (backend 0)
    (bootable 1)
    )
    )

    # Change to

    (device
    (tap
    (uname tap:aio:/xen/vm1/disk0)
    (uuid d2cb4a14-ecbd-6034-3d4c-7866bfd4b60e)
    (mode w)
    (dev xvda:disk)
    (backend 0)
    (bootable 1)
    )
    )

     
  3. Delete old DomU
    xm delete <DomU_ID>
  4. Load new configuration
    xm new -F /tmp/vm1.conf
  5. Start new DomU
    xm start <DomU_ID>

Additional Information

The advantage of the blktap is a better performance compared to disk images accessed through loopback.  The blktap driver is supported as of SLES10 SP2, however for NetWare this should only be used on NW65SP8.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7000716
  • Creation Date: 20-Jun-2008
  • Modified Date:14-Mar-2021
    • SUSE Linux Enterprise Server

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