Abstract: Disclosed is a solid state disk drive, including a volatile, electronic RAM, memory and a non volatile, magnetic disk. The drive continuously saves unique data stored in the memory back to the disk. Additionally, the drive includes a number of tables and bit fields, in both volatile electronic memory and disk, for generally keeping track of what data has been restored from disk to memory, what data in the memory has been modified since it was restored from disk, and what modified data in the memory has been saved back to disk. In the event of a primary power outage, the drive first saves the volatile tables onto disk, and then saves the volatile, modified data onto disk, while using auxiliary power. If, however, auxiliary power is lost before any or all of the modified data is saved on disk, the saved tables provide information which enables the drive to distinguish the valid from the invalid data on disk.