this was posted to samba-technical some time ago: I saw with recent Samba versions that TDBs are not written to disk while Samba is running, propably a problem of mmap'ed TDBs. So there was the problem that ID mappings which were updated on Friday where lost after a power loss on Saturday. Volker also mentioned that a customer saw this problem with recent Samba versions (3.0.14), while with 3.0.7 this problems never came up. This happens with 2.4 and 2.6 linux kernels.
*** This bug has been marked as a duplicate of 3101 ***