Hi, everyone: what's the purpose for LogEvent with empty metablob? For example in link/unlink operation cross two active mds, the procedure may look like below: 1. master send PREPARE to slave 2. slave receives PREPARE, and journal an ESlaveUpdate::OP_PREPARE, then responds ACK to master 3. master receives ACK and journal an EUpdate, then send OP_FINISH to slave 4. slave receives OP_FINISH and journal ESlaveUpdate::OP_COMMIT, then send OP_COMMIT to master 5. master receives OP_COMMIT and journal an ECommitted Why logevents in step 4 and 5 are necessary? Both of them have empty metablob. I guess these two logevents are originally used for a scene that crashes happen, but actually it seems not necessary. For example, if cash happens, after failed mds are brought up again, in resolve stage, master will resend OP_FINISH to slave, then things will continue as expected. Any tips about this question are appreciated. Thanks!