i probably should have have been clearer - the PC only contains a RAID array, and the OS resides on this RAiD array. GSmartControl does not provide any further menu options after double-clicking the volume on which the OS resides, it just provides information on the volume. So, it is not possible to just scan the volume containing the OS with GSmartControl.
THE RAID array software DOES have the ability to scan the volume in which the OS resides - it will scan all 5 HDDs together searching for RAID verification and media errors. Shall I try this first?