On Sat, 09 Aug 2014 16:37:52 -0400 Gary Dale <garyd...@torfree.net> wrote:
> The speed of the check is usually limited by the speed of reading the > file(s) from disk. A par2 check is more direct and will also > automatically repair any bit rot that has developed. Definitely not. For very small files nearly all methods of error checking are about the same. For large files, there are massive time differences between md5, sha1, par2. The longest time, by far, is par2 checking. I even did a simple check myself to ensure this is true... Here are the results: Summary: par2 verify about double time than sha1 for large files. sha1 verify about double time than md5 for large flies. par2 creation about 21 times longer than sha1 generation for large files. sha1 creation about double time than md5 for large files. ---------------------------------------------------------------------------------------------------- Details: For check generation: 10 x 1024 files for md5sum generation Elapsed time is 0.00465393 seconds. 10 x 1024 files for sha1sum generation Elapsed time is 0.00407004 seconds. 3 x 1GB and 2 x 2GB files for md5sum generation Elapsed time is 13.0712 seconds. 3 x 1GB and 2 x 2GB files for sha1sum generation Elapsed time is 22.3703 seconds. 10 x 1024 files for par2 generation Elapsed time is 0.0724349 seconds. 3 x 1GB and 2 x 2GB files for par2 generation Elapsed time is 471.907 seconds. ---------------------------------------------------------------------------------------------------- For verify of check: 10 x 1024 files for md5sum verify Elapsed time is 0.00395489 seconds. 10 x 1024 files for sha1sum verify Elapsed time is 0.00317788 seconds. 3 x 1GB and 2 x 2GB files for md5sum verify Elapsed time is 12.9887 seconds. 3 x 1GB and 2 x 2GB files for sha1sum verify Elapsed time is 22.6091 seconds. 10 x 1024 files for par2 verify Elapsed time is 0.019568 seconds. 3 x 1GB and 2 x 2GB files for par2 verify Elapsed time is 51.4989 seconds. ---------------------------------------------------------------------------------------------------- CPU: Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 8 On-line CPU(s) list: 0-7 Thread(s) per core: 2 Core(s) per socket: 4 Socket(s): 1 NUMA node(s): 1 Vendor ID: GenuineIntel CPU family: 6 Model: 26 Stepping: 5 CPU MHz: 1600.000 BogoMIPS: 6414.40 Virtualization: VT-x L1d cache: 32K L1i cache: 32K L2 cache: 256K L3 cache: 8192K NUMA node0 CPU(s): 0-7 ---------------------------------------------------------------------------------------------------- Memory: 24GB --Andrew -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/20140809180230.66a9d8c0fca51961ba036...@1024bits.com
