XenServer

Upgrade from an existing version

By upgrading from an existing installation of Citrix Hypervisor 8.2 Cumulative Update 1 to XenServer 8, you can retain your existing VMs, SRs, and configuration.

Perform a rolling pool upgrade to keep all the services and resources offered by the pool available while upgrading all hosts in the pool. This upgrade method only takes one XenServer host offline at a time. Critical VMs are kept running during the process by live migrating the VMs to other hosts in the pool.

You can complete a rolling pool upgrade in one of the following ways:

  • If you have a Premium Edition license, you can use the XenCenter Rolling Pool Upgrade wizard. This wizard organizes the upgrade path automatically and guides you through the upgrade procedure.

    For more information, see Rolling pool upgrade by using XenCenter.

  • You can use the xe CLI to perform a rolling pool upgrade manually by live migrating running VMs between XenServer hosts accordingly.

    For more information, see Rolling pool upgrade by using the xe CLI.

Can I upgrade?

Ensure that you are able to upgrade to XenServer 8:

  • Are your hosts currently running Citrix Hypervisor 8.2 Cumulative Update 1?

    If not, you cannot upgrade directly to XenServer 8. Instead, perform a clean installation. For more information, see Install.

  • Are you using a supported partition layout?

    The legacy partition layout is no longer supported. If you use it, you might not be able to upgrade to XenServer 8. For more information, see Legacy partition layout.

  • Are you using the Citrix Licensing Server virtual appliance?

    In previous releases, we supported the Linux-based License Server virtual appliance. This product is no longer supported. If you are using the License Server virtual appliance with an existing pool, migrate to the latest version of Citrix License Server for Windows before upgrading to XenServer 8. For more information, see Licensing.

  • Is the key size of the server’s identity certificate smaller than 2048 bytes?

    If your pool was first installed using XenServer 7.6 or earlier, it might still have certificates with a smaller key size than 2048 bytes. In this case, when you attempt to upgrade to XenServer 8, the upgrade wizard shows an error during prechecks. To proceed with the upgrade, you must reset the self-signed certificate on each affected server by running the following command:

     xe host-emergency-reset-server-certificate
    

    This command can interrupt ongoing operations in the pool.

  • Is your hardware compatible with XenServer 8?

    Check that the hardware your pool is installed on is compatible with the version of XenServer you are about to upgrade to. For more information, see the Hardware Compatibility List (HCL).

  • Are your VM operating systems supported by XenServer 8?

    Check that the operating systems of your VMs are supported by XenServer 8. If your VM operating system is not supported, upgrade your VM operating system to a supported version before upgrading XenServer. For more information, see Guest operating system support.

  • Are you using XenServer to host your Citrix Virtual Apps and Desktops workloads?

    You can upgrade to XenServer 8 by using the methods described in this article. However, depending on your XenServer environment and your Citrix Virtual Apps and Desktops workload, there might be specific behaviors and requirements to consider that can optimize your XenServer upgrade process. For more information, see Upgrade scenarios for Citrix Virtual Apps and Desktops.

Before you start

Review the following information before starting your upgrade. Take the necessary steps to ensure that your upgrade process is successful.

Plan for the upgrade

  1. Map your upgrade path carefully. Upgrading XenServer hosts, and particularly a pool of XenServer hosts, requires careful planning and attention to avoid losing any existing data.

    Note the following information when planning your upgrade:

    • You cannot migrate a VM from a newer version of XenServer to an older one.
    • Do not operate your pool in mixed-mode (with multiple versions of XenServer) for longer than is necessary. The pool operates in a degraded state during upgrade.
    • Key control operations are not available during the upgrade process. Do not attempt to perform any control operations.
    • Do not copy, shut down, or export VMs during the upgrade process.
    • Do not perform storage-related operations - such as adding, removing, or resizing virtual disks - during the upgrade process.
    • During the upgrade of the pool coordinator, the other hosts in the pool enter emergency mode.
  2. Ensure that your servers are not over-provisioned: check that servers have sufficient memory to carry out the upgrade.

    Generally, if N equals the total number of servers in a pool, there must be sufficient memory across N-1 servers to run all live VMs in the pool. It is best to suspend any non-critical VMs during the upgrade process.

  3. Ensure that your pool has shared storage to keep your VMs running during a rolling pool upgrade. If your pool does not have shared storage, you must suspend your VMs before upgrading because the VMs cannot be live migrated.

    Storage live migration is not supported with rolling pool upgrades.

  4. Note the following behaviors:

    • The upgrade must use the same boot mode as the initial install.

    • Boot-from-SAN settings are not inherited during the manual upgrade process. When upgrading using the ISO or PXE process, you must ensure that multipathd is correctly configured. For more information, see Boot from SAN.

    • When you upgrade XenServer, previously applied supplemental packs are removed and so they must be reapplied during or after the upgrade. However, the PVS-Accelerator supplemental pack is no longer required to be installed on XenServer 8. Its features are now included in the main product installation.

Prepare your pool

  1. Take a backup of the state of your existing pool using the xe CLI command xe pool-dump-database.

    Taking a backup of the state ensures that you can revert a partially complete rolling upgrade to its original state without losing VM data.

  2. Disable high availability.

Prepare your VMs

  1. If you have Windows VMs running in your pool, take the following steps for each VM:

    • Ensure that the latest version of the XenServer VM Tools for Windows is installed.
    • Take a snapshot of the VM.
  2. If you have Linux VMs running in your pool, ensure that the latest version of the XenServer VM Tools for Linux is installed.

  3. If you have NVIDIA vGPU-enabled VMs running on your pool, complete the following steps to migrate the pool while these VMs are running:

    1. Ensure that the GPU you are using is supported on the version you plan to upgrade to.
    2. Identify a version of the NVIDIA GRID drivers that is available for both your current version of Citrix Hypervisor or XenServer and the version of XenServer you are upgrading to. If possible, choose the latest available drivers.
    3. Install the new GRID drivers on your XenServer hosts and the matching guest drivers on any of your vGPU-enabled VMs.
    4. Ensure that you also have the version of the GRID driver that matches the XenServer version that you are upgrading to. You are prompted to install these drivers as a supplemental pack as part of the rolling pool upgrade process.
  4. Empty the CD/DVD drives of all VMs in the pool.

Get the required files

  1. If you are using XenCenter to upgrade your hosts, download and install the latest version of XenCenter from the XenServer download site.

    For more information, see Install XenCenter.

  2. Download the XenServer 8 installation ISO from the XenServer download site.

  3. Prepare the installation media:

    • To upgrade your hosts from a bootable USB, use a tool like rufus or diskpart to create a bootable USB by using the XenServer 8 installation ISO. Ensure that the tool does not alter the contents of the ISO file.

    • To upgrade your hosts from a CD, burn the XenServer 8 installation ISO file to a CD.

    • To upgrade your hosts from virtual media, go to the virtual console of your system and mount the XenServer installation ISO file as virtual media.

    • To upgrade from a network location:

      1. Set up a network-accessible TFTP server to boot the installer from.
      2. Set up a network location where you can access the installation ISO through HTTP, FTP, or NFS.
      3. Unpack the installation ISO onto the network location.

        If you are using IIS to host the installation media, ensure that double escaping is enabled on IIS before extracting the installation ISO on it.

      4. Make note of the information you need during the upgrade:

        • For HTTP or FTP, make note of the URL for your HTTP or FTP repository, and a user name and password, if appropriate.
        • For NFS, make note of the server and path of your NFS share.

      For more information, see Network boot.

After these prerequisite steps are completed, you can perform a rolling pool upgrade by one of the following methods:

Rolling pool upgrade by using XenCenter

The Rolling Pool Upgrade wizard guides you through the upgrade procedure and organizes the upgrade path automatically. For pools, each of the servers in the pool is upgraded in turn, starting with the pool coordinator. Before starting an upgrade, the wizard conducts a series of prechecks. These prechecks ensure certain pool-wide features, such as high availability, are temporarily disabled and that each server in the pool is prepared for upgrade. Only one server is offline at a time. Any running VMs are automatically migrated off each server before the upgrade is installed on that server.

Note:

The XenCenter Rolling Pool Upgrade wizard is only available if you have a Premium Edition license.

If you have not yet installed XenCenter, download the latest version from the XenServer download site and complete the steps in Install XenCenter.

The wizard can operate in manual or automatic mode:

  • In manual mode, you must manually run the XenServer installer on each server in turn and follow the on-screen instructions on the serial console of the server. When the upgrade begins, XenCenter prompts you to insert the installation media or specify a network boot server for each server that you upgrade.

  • In automatic mode, the wizard uses network installation files on an HTTP, NFS, or FTP server to upgrade each server in turn. This mode doesn’t require you to insert installation media, manually reboot, or step through the installer on each server. If you perform a rolling pool upgrade in this manner, you must unpack the installation media onto your HTTP, NFS, or FTP server before starting the upgrade.

To upgrade XenServer hosts by using the XenCenter Rolling Pool Upgrade wizard:

  1. On the XenCenter Tools menu, select Rolling Pool Upgrade.

  2. Read the Before You Start information. Click Next to continue.

  3. Select the pools and any individual hosts that you want to upgrade, and then click Next.

  4. Choose one of the following modes:

    • Automatic Mode for an automated upgrade from network installation files on an HTTP, NFS, or FTP server.

      If you choose Automatic Mode and are using IIS to host the installation media, ensure that double escaping is enabled on IIS before extracting the installation ISO on it.

    • Manual Mode for a manual upgrade either from a USB/CD/DVD or by using network boot (using existing infrastructure).

      If you choose Manual Mode, you must run the XenServer installer on each host in turn. Follow the on-screen instructions on the serial console of the host. When the upgrade begins, XenCenter prompts you to insert the XenServer installation media or specify a network boot server for each host that you upgrade.

  5. After you have selected your upgrade mode, click Run Prechecks.

  6. Follow the recommendations to resolve any upgrade prechecks that have failed. If you want XenCenter to resolve all failed prechecks automatically, click Resolve All.

  7. When all prechecks have been resolved, click Next to continue.

  8. Prepare the XenServer installation media.

    • If you chose Automatic Mode, enter the installation media details. Choose HTTP, NFS, or FTP and then specify the URL, user name, and password, as appropriate.

      Notes:

      • If you choose FTP, ensure that you escape any leading slashes that are in the file path section of the URL.

      • Enter the user name and password associated with your HTTP or FTP server, if you have configured security credentials. Do not enter the user name and password associated with your XenServer pool.

      • XenServer supports FTP in passive mode only.

    • If you chose Manual Mode, note the upgrade plan and follow the instructions.

  9. Click Start Upgrade.

  10. When the upgrade begins, the Rolling Pool Upgrade wizard guides you through any actions you must take to upgrade each host. Follow the instructions until you have upgraded and updated all hosts in the pools.

  11. If you have vGPU-enabled VMs, when you reach the step that gives you the option to supply a supplemental pack, upload the NVIDIA driver that matches the one on your vGPU-enabled VMs. Ensure you upload the version of the driver for the XenServer version you are upgrading to.

  12. The Rolling Pool Upgrade wizard prints a summary when the upgrade is complete. Click Finish to close the wizard.

Note:

If the upgrade or the update process fails for any reason, the Rolling Pool Upgrade wizard halts the process. This allows you to fix the issue and resume the upgrade or update process by clicking the Retry button.

After the upgrade

After your pool is upgraded, we recommend that you enable the certificate verification feature. For more information, see Certificate verification.

After a rolling pool upgrade is complete, a VM might not be located on its home host. To relocate the VM, you can do one of the following actions:

  • Live migrate the VM to its home host
  • Shut down the VM and then start it on its home host

Rolling pool upgrade by using the xe CLI

Before performing a rolling pool upgrade by using the xe CLI, ensure that you have completed all the prerequisite steps in Before you start.

Important:

Ensure that you upgrade all servers in your pool. We strongly advise against running a mixed-mode pool (one with multiple XenServer versions) for longer than necessary, as the pool operates in a degraded state during upgrade.

Key control operations are not available during the upgrade process. Do not attempt to perform any control operations. Though VMs continue to function as normal, VM actions other than migrate are not available (for example, shut down, copy and export). In particular, it is not safe to perform storage-related operations such as adding, removing, or resizing virtual disks.

To perform a rolling pool upgrade by using the xe CLI:

Start with the pool coordinator:

  1. Disable the pool coordinator. This prevents any new VMs from starting on or being migrated to the specified host.

    xe host-disable host-selector=<host_selector_value>
    
  2. Ensure that no VMs are running on the pool coordinator. Shut down, suspend, or migrate VMs to other hosts in the pool.

    • To shut down a VM, use the following command:

       xe vm-shutdown
      
    • To suspend a VM, use the following command:

       xe vm-suspend
      
    • To migrate a specific VM, use the following command:

       xe vm-migrate
      

      Migrating specified VMs to specified hosts gives you full control over the distribution of migrated VMs to other hosts in the pool.

    • To evacuate the host, use the following command:

       xe host-evacuate
      

      Evacuating all VMs from a host leaves the distribution of migrated VMs to XenServer.

  3. Shut down the pool coordinator.

    xe host-shutdown
    

    Important:

    You are unable to contact the pool coordinator until the upgrade of the pool coordinator is complete. Shutting down the pool coordinator causes the other hosts in the pool to enter emergency mode. Hosts can enter emergency mode when they in a pool whose pool coordinator has disappeared from the network and cannot be contacted after several attempts. VMs continue to run on hosts in emergency mode, but control operations are not available.

  4. Boot the pool coordinator using the XenServer installation media and method of your choice (such as, USB or network).

  5. Follow the XenServer installation procedure until the installer offers you the option to upgrade. Choose to upgrade.

    When your pool coordinator restarts, the other hosts in the pool leave emergency mode and normal service is restored after a few minutes.

  6. Start or resume any shutdown or suspended VMs.

  7. Migrate any VMs that you want back to the pool coordinator.

If anything interrupts the upgrade of the pool coordinator or if the upgrade fails for any reason, do not attempt to proceed with the upgrade. Reboot the pool coordinator and restore to a working version.

Repeat these steps for all the other hosts in the pool:

  1. Select the next XenServer host in your upgrade path. Disable the host.

    xe host-disable host-selector=<host_selector_value>
    
  2. Ensure that no VMs are running on the host. Shut down, suspend, or migrate VMs to other hosts in the pool.

    • To shut down a VM, use the following command:

       xe vm-shutdown
      
    • To suspend a VM, use the following command:

       xe vm-suspend
      
    • To migrate a specific VM, use the following command:

       xe vm-migrate
      

      Migrating specified VMs to specified hosts gives you full control over the distribution of migrated VMs to other hosts in the pool.

    • To evacuate the host, use the following command:

       xe host-evacuate
      

      Evacuating all VMs from a host leaves the distribution of migrated VMs to XenServer.

  3. Shut down the host.

    xe host-shutdown
    
  4. Boot the host using the XenServer installation media and method of your choice (such as, USB or network).

  5. Follow the XenServer installation procedure until the installer offers you the option to upgrade. Choose to upgrade.

  6. After the host upgrade is complete, start or resume any shutdown or suspended VMs.

  7. Migrate any VMs that you want back to the host.

If the upgrade of a subordinate host fails or is interrupted, you do not have to revert. Run the command xe host-forget in the pool to forget that host. Reinstall XenServer on the host, and then join it, as a new host, to the pool using the command xe pool-join.

After the upgrade

After your pool is upgraded, we recommend that you enable the certificate verification feature. For more information, see Certificate verification.

After a rolling pool upgrade is complete, a VM might not be located on its home host. To relocate the VM, you can do one of the following actions:

  • Live migrate the VM to its home host
  • Shut down the VM and then start it on its home host

Other scenarios

Legacy partition layout

The legacy partition layout is no longer supported. If you use it, you might not be able to upgrade to XenServer 8 and must instead perform a fresh installation.

XenServer 6.5 and earlier uses a 4 GB control domain (dom0) partition for all dom0 functions, including swap and logging. This partition configuration is referred to as the legacy partition layout. Later releases of XenServer and Citrix Hypervisor introduced a partition layout that increased the control domain partition to 18 GB and included a separate logging partition. In XenServer 8, only the newer partition layout is supported.

How do I know what partition layout my server uses?

You might have the legacy partition layout on your XenServer hosts in the following cases:

  • You initially installed your XenServer host with XenServer 5.6 Service Pack 2 or earlier and have since upgraded to later supported versions.

  • You are using old hardware that has less than 46 GB of primary disk space.

  • Your hardware requires that a utility partition is present.

To find out how many partitions your XenServer host has, run the following command in the server console:

fdisk -l
  • If the command lists 6 partitions, you are using the new partition layout and can upgrade to XenServer 8.
  • If the command lists 3 or 4 partitions, you are using the legacy partition layout.

What can I do next?

If you are using the new partition layout, you can upgrade to XenServer 8.

If you are using the legacy partition layout:

  • If you have less than 46 GB of primary disk space or your hardware requires that a utility partition is present, you cannot install or upgrade to XenServer 8.
  • If your disk is GPT and the local SR is empty with at least 38 GB free, you can switch from the legacy partition layout to the new partition layout during upgrade. You must use XenCenter to attempt the upgrade on a server with the legacy partition layout. For more information, see Rolling pool upgrade by using XenCenter.
  • For other hardware, you can complete a fresh installation of XenServer 8. For more information, see Install.

Citrix Virtual Apps and Desktops environments

If you are using XenServer to host your Citrix Virtual Apps and Desktops workloads, see Upgrade scenarios for Citrix Virtual Apps and Desktops.

Upgrade from an existing version