You at least have to retain data long enough for the followers to be able
to copy it from the leader. As Jun mentioned, you can observe the max lag
in the
follower and set replica.lag.max.messages to be a little higher than that.
The high watermark is incremented to point to the logical offset of the
latest message that has been copied to all the replicas in the ISR. Once
the high watermark includes a certain message, it is considered
"committed". So it is not configurable.

On Tue, Sep 10, 2013 at 8:26 AM, Yu, Libo <[EMAIL PROTECTED]> wrote:
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