From: Johan De Meersman Date: January 8 2013 10:43am Subject: Re: Percona 5.5 semisynchronous replication. List-Archive: http://lists.mysql.com/mysql/228863 Message-Id: <1329653.11870.1357641795590.JavaMail.root@tuxera.be> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable ----- Original Message ----- > From: "Rafa=C5=82 Radecki" >=20 > Seconds_Behind_Master: 364 >=20 > So if I have rpl_semi_sync_master_timeout=3D5000 (5s) and semisync >=20 > why is it possible on the slave to fall behind the master? Semi-sync only guarantees that the slave has *received* the statement in it= 's relay log. The rpl_semi_sync_master_timeout value is the timeout for the= slave to acknowledge this, whereas the Seconds_Behind_Master value gives a= n indication of how far statement *execution* is lagging. --=20 Unhappiness is discouraged and will be corrected with kitten pictures.