You manage your existing virtual environment by using Microsoft System Center Virtual Machine Manager （VMM） 2008 R2. You are designing a highly available Hyper-V solution. You need to minimize the downtime of virtual machines （VMs） during maintenance periods. What are two possible ways to achieve this goal？（）

Create a host group that contains Server1 and Server2， and place each VM on NFS storage

Create a Hyper-V failover cluster of Server1 and Server2， and place each VM on a separate shared iSCSI logical unit number （LUN）

Create a Hyper-V failover cluster of Server3 and Server4， and place all VMs on a single Fibre Channel logical unit number （LUN）

Create a Hyper-V failover cluster of Server3 and Server4， and place all VMs on a single iSCSI logical unit number （LUN） that is configured as a Cluster Shared Volume （CSV）