Home > Data Protection > PowerProtect DD Series Appliances > PowerProtect Appliance Data Invulnerability Architecture > “On-the-fly” error detection and correction
To ensure that all data returned to the user during a restore is correct, the PowerProtect Appliance file system stores all its on-disk data structures in formatted data blocks. These data blocks are self-identifying and verified by a strong checksum. On every read from disk, the system first verifies that the block read from disk is the block expected. It then uses the checksum to verify the integrity of the data. If any issue is found, the system prompts RAID 6 to use its extra level of redundancy to correct the data error. Because the RAID stripes are never partially updated, their consistency is ensured, as is the ability to heal an error when it is discovered.