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Upon restart, we should drop the corrupted part of the log and log. It will be replicated once again from the leader.

Fsync

Different levels of guarantees are possible:

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More on all these options is later in the document. Considering statements above, we could have different fsync policies, not just “enabled/disabled”.

Resulting issues with the data

What happens when partition loses part of the log? It happens with manual peers/learners configuration updates or while losing part of the log. The most extreme case of it - total partition loss.

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