A software upgrade is a major, standalone version of XenServer. Upgrade to add new features or technologies, or to replace a release that is no longer supported. A software update updates a major version of XenServer, but does not upgrade it to the next major version.
XenCenter is configured by default to automatically check for new XenServer and XenCenter updates and upgrades at regular intervals, and you will be notified when a new update or product version is available. It is recommended that you install all published updates. You can check for available updates manually at any time and verify that you are running the latest version of both XenServer and XenCenter by choosing option.
Updates for XenServer are supplied as files with the file extension .xsupdate (or .xsoem for embedded servers running older versions of XenServer). Once they have been downloaded, XenServer updates, including critical updates, hotfixes, and security updates, can be quickly applied to your managed servers; see Updating managed servers for details.
Updates for XenCenter are supplied as Windows installer (.msi) packages which can be downloaded and installed using a Download Manager; see Updating XenCenter.
To upgrade XenServer hosts, use the Rolling Pool Upgrade wizard. You can use this wizard to upgrade multiple servers in a pool with minimal service interruption for running VMs. VMs are automatically migrated onto other available servers as the upgrade is applied to each server in turn. The wizard can also be used to upgrade individual servers.