How to Configure Multipath Boot from SAN during XenServer Upgrade or Patch

How to Configure Multipath Boot from SAN during XenServer Upgrade or Patch

book

Article ID: CTX137410

calendar_today

Updated On:

Description

This article describes how to configure multipath boot from Storage Area Network (SAN) when upgrading or patching XenServer. The upgrade or patching of XenServer can leave the initial ram disk (initrd) without multipath support.

Instructions

To configure multipath support, complete the following procedure:

  1. Before the upgrade or update, ensure the host has the Root Disk Multipathing section visible on the General tab in XenCenter – This indicates that the host has been installed correctly.

  2. For upgrading to a new version, console/vga access is necessary. Refer the section Boot From SAN Environments of Appendix B in CTX134586 - XenServer 6.1.0 Installation Guide.

  3. At the welcome screen, press F2 and enter multipath on the prompt.

  4. Ensure the /etc/multipath.conf file is configured properly for the storage subsystem to be used for the Root Disk Multipathing.

  5. For a new kernel installation from a HotFix (HotFix 14 on XenServer 6.1.0), the HotFix installation generates a new initrd for the host that should include the proper multipath device specified as the root disk.
    After the restart if it does not show Root Disk Multipathing, then restart from the previous kernel by running menu.c32 at the boot prompt of the XenServer host and select the option for the previous kernel.
    After the restart, open console on the host server and create the proper script to recreate the initrd. Refer the following procedure. Rename the original initrd created during the HotFix installation and run the created script.

  6. Restart the host from XenCenter. Root Disk Multipathing is active now.

To generate an initrd creation script and a new initrd, complete the following procedure:

  1. Open the console with root access and run ls /boot/initrd*xen* to see the current initial ramdisk files on the XenServer.
    Example: initrd-2.6.32.12-0.7.1.xs6.0.0.541.170669xen.img.
    The script file also is visible for the original GA kernel. 6.0.0 .
    Example: initrd-2.6.32.12-0.7.1.xs6.0.0.529.170661xen.img.cmd.

  2. Generate the new script file to match the new kernel: cd /boot
    cp initrd-2.6.32.12-0.7.1.xs6.0.0.529.170661xen.img.cmd initrd-2.6.32.12-0.7.1.xs6.0.0.541.170669xen.img.cmd
    Note the two number changes that are necessary: 529 becomes 541 and 170661 becomes 170669 in the current example of XenServer 6.0.0 and HotFix 16.

  3. Modify the contents of the script file so that it creates the correct initrd for the correct kernel:
    sed -ibak -e 's/529/541/g' -ibak -e 's/170661/170669/g' <new script file name>

  4. Then execute the script:
    . ./<script file name>

  5. Use ls -l to verify if the new initrd file exists. The existing symlinks for the xe default boot option automatically works as the new initrd replacing the original initrd.

Environment

The above mentioned sample code is provided to you as is with no representations, warranties or conditions of any kind. You may use, modify and distribute it at your own risk. CITRIX DISCLAIMS ALL WARRANTIES WHATSOEVER, EXPRESS, IMPLIED, WRITTEN, ORAL OR STATUTORY, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NONINFRINGEMENT. Without limiting the generality of the foregoing, you acknowledge and agree that (a) the sample code may exhibit errors, design flaws or other problems, possibly resulting in loss of data or damage to property; (b) it may not be possible to make the sample code fully functional; and (c) Citrix may, without notice or liability to you, cease to make available the current version and/or any future versions of the sample code. In no event should the code be used to support ultra-hazardous activities, including but not limited to life support or blasting activities. NEITHER CITRIX NOR ITS AFFILIATES OR AGENTS WILL BE LIABLE, UNDER BREACH OF CONTRACT OR ANY OTHER THEORY OF LIABILITY, FOR ANY DAMAGES WHATSOEVER ARISING FROM USE OF THE SAMPLE CODE, INCLUDING WITHOUT LIMITATION DIRECT, SPECIAL, INCIDENTAL, PUNITIVE, CONSEQUENTIAL OR OTHER DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. Although the copyright in the code belongs to Citrix, any distribution of the sample code should include only your own standard copyright attribution, and not that of Citrix. You agree to indemnify and defend Citrix against any and all claims arising from your use, modification or distribution of the sample code.

Issue/Introduction

How to Configure Multipath Boot from SAN when Upgrading/Patching XenServer.
Powered by Wolken Software