Product : Citrix, Citrix Hypervisor/8, Premium
Feature : Hypervisor Upgrades, Updates and Backup, Management
Content Owner:  Roman Macek
The XenCenter released with XenServer 7.0 allows updates to be applied to all versions of XenServer (commercial and free)
XenServer 7.1 introduced Live patching
With XenServer 7.0 patching and updating via the XenCenter management console (enabling automated GUI driven patch application and upgrades) is supported with the comercial and free XenServer versions.

XenServer 6 introduced the Rolling Pool Upgrade Wizard. The Wizard simplifies upgrades to XenServer 6.x by performing pre-checks with a step-by-step process that blocks unsupported upgrades. You can choose between automated or semi-automated, where automated can use a network based XenServer update repository (which you have to create) while semi-automated requires local install media. There are still manual steps required for both approaches and no scheduling functionality or online repository is integrated.

Indroduced in Xenserver 7.1, live patching enables customers to install some Linux kernel and Xen hypervisor hotfixes without having to reboot the hosts. Such hotfixes will consist of both a live patch, which will be applied to the memory of the host, as well as a hotfix that updates the files on disk. This reduces maintenance costs and downtime. When applying an update using XenCenter, the Install Update wizard checks whether the hosts need to be rebooted after the update is applied and displays the result on the Prechecks page. This enables customers to know the post-update tasks well in advance and schedule the application of hotfixes accordingly.
Citrix Hypervisor Live Patching is available for Enterprise Edition customers, or those who have access to Citrix Hypervisor through their XenApp/XenDesktop entitlement.