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Re: (ITS#7472) syncrepl conflicting write resolution trouble

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.

-- 
   -- Howard Chu
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