Talk:Development ideas

Data Integrity section.

• The idea of 64k chunks per allocation for checksums is what's termed a hash list
  • http://en.wikipedia.org/wiki/Hash_list
• which can be extended to a multi-level hash tree
  • http://en.wikipedia.org/wiki/Hash_tree

• One could imagine a 3-level tree
  • a hash for each lowest-common-unit, say the commonly used 1 Kbyte data size
  • a single top hash for each IBP allocation
  • a single top hash for the file
  • or more levels if there more natural subdivisions

• It seems to be common in distributed systems to use a binary hash tree rather than a hash list even on individual data blocks.
  • Tiger Tree Hash TTH is the most? popular since it provides both high performance and high security
  • http://en.wikipedia.org/wiki/Tiger_%28hash%29
  • http://en.wikipedia.org/wiki/Hash_tree#Tiger_tree_hash

If the IBP protocol were to be extended to support a single specific checksum method it would possibly be something like TTH. In this example, this would mean TTH usage becomes part of the IBP protocol and both the client and depot would have to implement it.

- Dan 1/24/08