[KUDU-1039] Prevent users from setting --log_min_segments_to_retain to 0

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: Feature Complete
• Component/s: log
• Target Version/s: Public beta
• Code Review: http://gerrit.sjc.cloudera.com:8080/7601
• Assignee: Todd Lipcon
• Reporter: Mike Percy
• Created: 19/Aug/15 21:55
• Updated: 25/Aug/15 17:05
• Resolved: 25/Aug/15 17:05

Description

If a user sets min log retention to 0, and the tablet quiesces, it may be possible that we shut down with only an empty log file. This would make it impossible to start back up and we need to prevent this configuration.

See TabletBootstrap::Bootstrap() in tablet_bootstrap.cc around this code block for the reasoning:

  if (has_blocks && !needs_recovery) {
    return Status::IllegalState(Substitute("Tablet: $0 had rowsets but no log "
                                           "segments could be found.",
                                           tablet_id));
  }

Not to mention that we will have no way of knowing what the next index in the log should be, so we can't safely do anything Rafty like participate in leader elections, etc.