An array is making clicking noises.

Upon identifying a potential cause of an issue with a RAID 5 array, especially when the array is making clicking noises that suggest a failing drive, the next critical step is to perform a full data backup. This ensures that data is preserved before any further troubleshooting steps are taken, such as replacing the failing drive. RAID 5 provides fault tolerance, but ensuring data is backed up minimizes the risk of data loss during the repair process.