Github user andytaylor commented on the issue:
https://github.com/apache/activemq-artemis/pull/1747
Michael is correct, that's what I meant. Let me explain how this works.
Every record that is written to the journal is also sent to the backup.
Once the backup receives the packet it responds with an ack and in parallel
writes it to disc.
When the live crashes the back up fsyncs and then starts.
There is a small window between when the live crashes and when the fsync
occurs that the backup may crash, but this is unlikely to happen and you stil
have data consistency as the journal is on the live.
The caveat here is if the disc on the live was destroyed, but again the
window is so small there are more likely scenarios that we could improve from a
crash pov.
@shoukunhuai Why don't you explain your use case, not in an implementation
way but something like 'when x happens I want to avoid y'.
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