Add a dedicated mirror that is a different set of disks than the R10 array, if 6 or more disks are possible.

Create amount point of VG_BACKUPS on the extra mirror or at the root of the R10 array if there is no mirror.

Create in /mnt directories for each virtualization host e.g.

/mnt/VHSRV01
/mnt/VHSRV02
/mnt/VHSRV03

Add to these sub directories VG_IMAGES and VG_BACKUPS e.g.

/mnt/VHSRV01/VG_IMAGES
/mnt/VHSRV01/VG_BACKUPS
/mnt/VHSRV02/VG_IMAGES
/mnt/VHSRV02/VG_BACKUPS
/mnt/VHSRV03/VG_IMAGES
/mnt/VHSRV03/VG_BACKUPS

VG_IMAGES should correspond to /var/lib/libvirt/images on the NFS server for each virtualization host
VG_BACKUPS should correspind to var/lib/libvirt/images/VG_BACKUPS on the NFS server for each virtualization host (if a separate set of disk is dedicated to backups then use /VG_BACKUPS)

Add NFS mounts to each virtualiztion hosts fstab according to virtulization setup document. Try to minimize the # of NFS shares that are mounted so as to prevent issues when virtualizations hosts are rebooted.