System for rebuilding dispersed data

Abstract

A digital data file storage system is disclosed in which original data files to be stored are dispersed using some form of information dispersal algorithm into a number of file 'slices' or subsets in such a manner that the data in each file share is less usable or less recognizable or completely unusable or completely unrecognizable by itself except when combined with some or all of the other file shares. These file shares are stored on separate digital data storage devices as a way of increasing privacy and security. As dispersed file shares are being transferred to or stored on a grid of distributed storage locations, various grid resources may become non-operational or may operate below at a less than optimal level. When dispersed file shares are being written to a dispersed storage grid which not available, the grid clients designates the dispersed data shares that could not be written at that time on a Rebuild List. In addition when grid resources already storing dispersed data become non-available, a process within the dispersed storage grid designates the dispersed data shares that need to be recreated on the Rebuild List. At other points in time a separate process reads the set of Rebuild Lists used to create the corresponding dispersed data and stores that data on available grid resources.