[erlang-questions] auto-syncing mnesia after a network split

Chandru <>
Mon Dec 8 13:52:13 CET 2008


2008/12/8 mats cronqvist <>:
> Claes Wikström <> writes:
>
>> mats cronqvist wrote:
>>> "Felix Hamilton" <> writes:
>>>
>>>> I have used NTP (the Network Time Protocol) quite effectively to sync
>>>> timestamps in widely distributed systems with a fairly high degree of
>>>> accuracy.
>>>
>>>   i personally would not bet a dirty sock on ordering events by time
>>>   stamps (in a distributed system). and for once Leslie Lamport seems
>>>   to agreewith me.
>>>
>>
>> I think I would. In retrospect I think the worst part of mnesia (apart
>> from the sucky dets module I once wrote) is how we chose to deal with
>> partitioned networks.
>>
>> We should have chosen to rely on the system clock. For example if
>> all nodes make a persistent note of when they lost contact with other
>> nodes. Once they reunite they could compare timestamps, and also compare
>> timestamps on the last committed transaction.
>> In a vast majority of cases it would be possible to automatically chose
>> a winner.
>
>  and what would happen in the small minority of cases?

I presume it would be whatever happens today -- nothing.

Chandru



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