What are the principle of and purpose for a disk media scan?
The storage system periodically scans all hard disks for potential errors.
Not only RAID group member disks, but also hot spare disks and free disks are scanned to ensure that all disks are available when they are required.
The default scan period is 30 days. All disks are scanned during the scan period. If the number of disks in the system is more than 100, you are advised to set the scan period to 60 days to decrease the performance compromising caused by the scanning.