Method for reducing data loss and unavailability by integrating multiple levels of a storage hierarchy

A method for reducing data loss in a system having a storage hierarchy, comprising:

• receiving a read request for read data;
• recognizing a data failure in a storage device in response to the read request;
• determining if RAID protection can handle the data failure;
• searching for a cached source of the read data in response to recognizing the data failure if said RAID protection can not handle the data failure;
• writing the read data in cache back to the storage device in which a data failure occurred if the read data was found in cache;
• determining if the read data containing the error has been allocated for storing;
• writing a blank data block back to the device in which a data failure occurred if the read data containing the error has not been allocated;
• retrieving the read data from a backup system if the cached source of the data is unavailable;
• determining if the read data has been updated since the last backup;
• determining read data updates pertaining to the read data;
• and
• rebuilding the read data utilizing a combination of the retrieved data updates and the data from the alternate source.