The Solaris Management Console Mounts and Shares tool cannot modify mount options on system-critical file systems such as root (/), /usr, and /var.
Workaround: Choose one of the following workarounds:
Use the remount option with the mount command.
# mount -F file-system-type -o remount,additional-mount-options \ device-to-mount mount-point
Mount property modifications that are made by using the -remount option with the mount command are not persistent. In addition, all mount options that are not specified in the additional-mount-options portion of the previous command inherit the default values that are specified by the system. See the man page mount_ufs(1M) for more information.
Edit the appropriate entry in the /etc/vfstab file to modify the file-system mount properties, then reboot the system.