z/VM version 6.2 introduced new capabilities for virtualization including Single System Image (SSI) clustering and Live Guest Relocation (LGR). SSI allows up to four z/VM systems to be managed as a single cluster, while LGR allows virtual machines to be moved between systems without disruption. Developing these features required addressing challenges like maintaining system architecture accuracy and flexibility across different hardware. Relocation domains were introduced to control where guests can move and the architecture features exposed. Overall, z/VM 6.2 significantly expanded the possibilities for virtualization on the IBM mainframe.