Select the calculation engine of the key file according to size. The calculation methods are:
1. SHA1: Calculating slow and the maximum accuracy (recommended for file sizes up to 100 Mbytes);
2. MD5: Calculating slow and the maximum precision (we recommend the use of SHA1 because more powerful than in the calculation);
3. SIZE + CR32: fast calculation but it can generate false in case of duplicate files small so we recommend the use of this algorithm only for files over 100MB.
4. SIZE + CR32 (xxxMB): Calculation of fast but can lead to false in case of duplicate files small so we recommend the use of this algorithm only for files over 100MB. The calculation of the CR32 is performed by reading the file every 1MB xxxMB or for a 1GB file-mode SIZE + CR32 (5MB) are read only about 200 MB;
5. SIZE: Calculation based solely on file size. If neither are strongly advised not to use except in special cases;