US Patent 9098447 Recovery of corrupted erasure-coded data files

If none of the fragments of an erasure-coded data file have become corrupted then the original data file can be readily reconstructed. If one or more fragments of an erasure-coded data file have become corrupted it may still be possible to find a combination of fragments that reconstruct the original data file, but the number of possible combinations may be impracticably large. If an attempt with a first set of fragments fails, an efficient approach is to use an independent set of fragments for the second attempt. Then, for further attempts, the results of a current attempt are compared with previous results. If a match is found then the original data file has been reconstructed. An original data file may also be reconstructed by separately recovering each data block of the data file from corresponding fragment blocks and assembling the data file from the recovered data blocks.