If your system has RAIDiator 4.0+ on it, and you are having issues with the Volume Check on boot up, it is possible to skip the volume check.
(Sparc) To do this, start with the system off, then turn it on, while depressing the power button for 5 seconds (1 long flash). Users with an LCD on their ReadyNAS will see '5: Skip Vol Check'.
(x86/ARM) To do this follow the steps described in the boot menu: http://www.readynas.com/kb/faq/boot/how_do_i_use_the_boot_menu
Skipping the volume check is not wise unless you are experiencing problems. It is wise to send your system logs to support for investigation to see why your volume check was having issues. If you open an online case for this issue you should see the option to attach your logs zip file to your case.