Block Level Incremental Backup With Brotli Compression

Block level incremental backup is one in which successive copies of the data contain only the portion that has been changed since the preceding backup. It backs up only the blocks within the file that was changed. Most of the existing backup system perform file level backup which takes up lot of storage space. Existing block level incremental backup algorithm including `rsync' works with MD5 hash function. Hash functions are difficult to calculate and also take memory for storing hash table. The proposed method uses bit map to identify block that was modified. Bit map takes less space than that of hash table moreover it does not need excessive computation. Furthermore `brotli' compression can be used to reuse the storage space taken for each backup. Brotli is a data format specification for data streams compressed with a specific combination of the general-purpose LZ77 lossless compression algorithm and Huffman coding. Brotli is independent of CPU type, operating system, file system, and character set. It has higher compression ratio and decompresses quickly when com-pared with other existing compression techniques like gzip, LZMA, etc.