Live Patching in Citrix Hypervisor

Citrix Hypervisor customers who deploy Citrix Hypervisor hosts may often need to reboot their servers after applying hotfixes. This rebooting results in unwanted downtime for the servers while customers have to wait until the system is restarted. Reboots reduce the uptime of the servers and impact business. Live patching enables customers to install some Linux kernel and Xen hypervisor updates without having to reboot the servers. This feature reduces maintenance costs and downtime. Such hotfixes consist of the following components:

  • A live patch that is applied to the memory of the server
  • A hotfix that updates the files on disk

Live Patching is enabled by default. For more information about enabling and disabling Live Patching, see Change Pool Properties.

When applying an update using the Install Update wizard, the Prechecks page displays information about the post-update tasks. Complete these tasks for the update to take effect. In addition, the wizard checks whether you must reboot the servers after applying the update and displays the result. This feature enables customers to know the post-update tasks well in advance and schedule the application of updates accordingly.

Note:

Live Patching is available for Citrix Hypervisor Premium Edition customers, or customers who have access to Citrix Hypervisor through their Citrix Virtual Apps and Desktops entitlement. For more information, see About Citrix Hypervisor Licensing.

Live patching scenarios

Hotfixes can be live patched across pools, servers, or on a standalone server. Some updates might need you to reboot the server, some need the XAPI toolstack to be restarted, and a few updates do not have any post-update tasks.

The following scenarios describe the behavior when a Live Patch is and is not available for an update:

  • Updates with live patch Hotfixes that update Linux kernel and the Xen hypervisor usually do not need a reboot after applying the update. However, in some rare cases, when the live patch cannot be applied, a reboot may be required.
  • Updates without live patch -No change in the behavior here. It works as usual.

Note:

If a server doesn’t require a reboot or if the update contains live patches that can apply to the servers, XenCenter displays No action required on the Update Mode page.

Live Patching in Citrix Hypervisor