As per Bug 1131247, user has to add '--reserved-percent' or '--reserved-space' to volgroup when using 'logvol --thinpool --grow', otherwise there will be no free space in volume group.
Assigning to Tahlia for review.
Reviewed and merged
Now published at https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.1/html/installation_guide/advanced_rhvh_install