ebackes@symas.com wrote:
Full_Name: Emily Backes Version: 2.4.33+ITS#7427 OS: URL: Submission from: (NULL) (98.155.30.248)
We are seeing a condition under heavy conflicting-write load-- i.e. changes to the same DN from multiple nodes in a syncrepl MMR cluster at the same time-- where the content of the entry is desynchronized between servers.
There is a non-reproduced case with incomplete logs where servers traded entry versions, even with one CSN significantly (by one second) later than the other. I'll supply more info if that reappears.
Additionally, we have a -d logged case of a conflicting write resulting in different changes applied on different servers while the same CSN gets applied to both, which seems truly bizarre.
The expected case is that one server "wins" the conflict and its state is sent to all of the others, eventually.
Analyzing the logs shows this is an unresolvable conflict in plain syncrepl/MMR. Please note that the Admin Guide already documents the fact that consistency is not guaranteed in this mode. (Section 18.2.2.3.)
The solution, as documented, is to use mirrormode.
All of these results are using back-hdb. More details soon, hopefully.