The Citrix XenServer Rolling upgrade feature was introduced in Citrix XenServer 5.6 Feature Pack 1. This is a fantastic wizard that will upgrade all your XenServers automatically to the latest version from a central FTP/HTTP or NFS network share. So instead of upgrading hundreds of XenServers manually with DVD/USB you can now use this tool instead.
There’s currently a lot of threads on the Citrix Forum so I thought it would be nice to provide a detailed guide on how to do this with NFS.
First of you’ll need to upgrade Citrix XenCenter to the latest version and setup a NFS share with the extracted content of the latest XenServer-6.0.201-install-cd.iso. To extract ISO files you can use Pismo File Mount or WinRAR.