Hi, cephers: What's the purpose of using LogEvent with empty metablob? For example in link/unlink operation cross two active mds, when slave receives OP_FINISH it will write an ESlaveUpdate::OP_COMMIT to the journal, then send OP_COMMITTED to master. When master receives OP_COMMITTED it will write an ECommitted to the journal then allow previously logged journal to be trimmed. Why are these two logevents necessary? I guess they are originally used for a scene that crashes happen, but in my opinion 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. Could anyone give some tips on this doubt? Sincerely thanks!