Home > Data Protection > PowerProtect DD Series Appliances > PowerProtect DD Data Invulnerability Architecture: Enhancing Data Integrity and Recoverability > Persistent RAM protection
In some smaller Data Domain systems, the entire system is protected from a power loss by a battery backup. For these systems, a persistent RAM implementation protects data in RAM. Data Domain systems move data from RAM to disk in a process called vaulting. If a power failure occurs, a battery powers the entire Data Domain system while data is vaulted from RAM to disk. If a system crashes, the system reboots into a special vaulting mode where it vaults data from RAM to disk and then reboots to normal DD OS.
This persistent RAM feature maintains power and control to the system RAM through a crash so that the contents of RAM are preserved across the crash. Persistent RAM implementations protect data during an AC power loss, a system reboot and shutdown, and a DD OS or kernel crash. The data vaulted to disk is RAID-protected, just like the Data Domain file system.