Live Patching in XenServer

XenServer customers who deploy XenServer 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 till the system is restarted. This also reduces the uptime of the servers and impacts business. Live patching enables customers to install some Linux kernel and Xen hypervisor updates without having to reboot the servers. This reduces maintenance costs and downtime. Such hotfixes will consist of both a live patch, which will be applied to the memory of the server, as well as 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 that customers are required to carry out for the update to take effect. In addition, the wizard also checks whether the servers need to be rebooted after the update is applied and displays the result. This enables customers to know the post-update tasks well in advance and schedule the application of updates accordingly.

Note: XenServer Live Patching is available for XenServer Enterprise Edition customers, or those who have access to XenServer through their Citrix Virtual Apps and Desktops entitlement. For more information about licensing, see About XenServer Licensing.

Live Patching Scenarios

Hotfixes can be live patched across pools, servers, or on a standalone server. Some updates may need reboot, 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 does not require a reboot, or if the update contains live patches that can be successfully applied to the servers, XenCenter displays No action required on the Update Mode page.

Live Patching in XenServer

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