When using NFS shared storage for Compute instance storage, Red Hat recommends that you mount the share with the noac or the lookupcache=none option to prevent NFS clients from caching file attributes (for details, see the NFS man page). This enables migration and resizing instances between compute hosts that use the shared storage, but with slight performance penalties. In a future release of RHOS, this requirement may be removed; the Release Notes will be updated when it is safe to use NFS shared storage for the Compute instance store without enabling the noac or lookupcache=none option.