Streams are segmented across sets of bookies called ensembles. http://distributedlog.incubator.apache.org/docs/latest/basics/introduction#log-segments
So loss of 3 bookies (assuming ensemble size 3) would never result in loss of an entire stream. Regardless, losing all replicas is non-recoverable if it happens all at once. If we lose all copies there's nothing to repair from. This scenario should be rare though. In production it is advised to run the BookKeeper ReReplicator, which continuously monitors for under replicated ledgers, and repairs the quorum continuously. As long as there is enough time to copy data between bookie deaths, you'd be fine. On Thu, Sep 29, 2016 at 9:57 PM, Jay Juma <[email protected]> wrote: > Can anyone share me more details about how does DL repair replicas? > > For example, if a stream is stored in bookie A, B, C and C is gone forever. > How does DL handle it? > > - Jay >
