As storage capacity increases so does the time it takes for RAID rebuilds to complete if a drive fails. With RAID 5 this means a longer period of time that your backups are exposed to complete failure. The longer the rebuild time the greater the chance that there could actually be a second drive failure. Vendors need to provide a better solution. With RAID 6 while you can sustain a second failure without data loss overall backup and recovery performance is still impacted. The other option is to use intelligence to mark out the bad section of the drive and keep on going.”]
Source: https://www.darkreading.com/database-security/backup-deduplication-2-0-needs-better-raid