As I understand it, there is no way to fix a problem with the algorithm of a defined checksum without invalidating existing zfs filesystems. Any fix to to the fletcher2 will have to be given a new name.
Given how incredibly weak the current fletcher2 is, perhaps the first thing that should be done is to change the default to fletcher4. The flawed fletcher2 appears to be 32768 times weaker than the 16 bit TCP checksum algorithm, i.e. it appears to only have a 50% chance of catching a single bit error or any series of single bit errors in the most significant bit of any 64 bit word in a disk block. For those bits, it is equivalent to a *1 bit* checksum. -- This message posted from opensolaris.org
