Reinder Cuperus <rein...@snt.utwente.nl> writes: > The problem is, as soon as I stop that connection, that master2 and > master3 have different gtid-positions for domain0, and stop/start on > replication master3->backup results in the error: > "Got fatal error 1236 from master when reading data from binary log: > 'Error: connecting slave requested to start from GTID 0-1-3898746614, > which is not in the master's binlog'
Yes. backup sees that it is ahead of master3 in domain 0, so it aborts to avoid risk of diverging replication. > I have tried moving master1/2 to domain_id:1, and removing the > domain_id:0 from the gtid_slave_pos on backup, but starting the > replication master2->backup results in the error: > Got fatal error 1236 from master when reading data from binary log: > 'Could not find GTID state requested by slave in any binlog files. > Probably the slave state is too old and required binlog files have been > purged.' Yes. Because backup now sees that it is far behind in domain 0 (as it sees the world), and aborts to not silently lose transactions. > I tried finding a way to purge domain:0 from master3/master4, but the > only way sofar I have found is doing a "RESET MASTER" on master3, which > would break replication between master3 and master4. Yes, I guess this is what you need. You have made a copy and removed half of the data, and now you need to similarly remove half of the binlog. Even if there are no actual transactions left from a domain in non-purged binlogs, the binlogs still remember the history of all domains, in order to not silently lose transactions for a slave that gets far behind. It would be useful in general to be able to purge a domain from a binlog. But currently the only way I can think of is RESET MASTER. You can see how this binlog history looks by checking @@gtid_binlog_state, and in the GTID_LIST events at the head of each binlog file. > I have tried to find a way to insert an empty transaction, with the last > gtid on domain_id:0 on the master3, to bring master2/master3 in sync > again on that domain, but I could not find a way to do that on MariaDB. The server will not binlog an empty transaction, but a dummy transaction should work, eg. create and drop a dummy table, for example: CREATE TABLE dummy_table (a INT PRIMARY KEY); SET gtid_domain_id= 0; SET gtid_server_id= 1; SET gtid_seq_no= 3898746614; DROP TABLE dummy_table; Maybe this way you can make the binlogs look like they are in sync to the replication, not sure. It might be tricky, but then you do seem to have a good grasp of the various issues involved. > Are there other ways to fix this issue, so I can have reliable > replication master3->backup without having to keep the dummy replication > backup->master3 indefinitely? I guess you would need to stop traffic to master3/master4 while getting them in sync with one another and the do RESET MASTER on both and SET GLOBAL gtid_slave_pos="" to start replication from scratch. You would then also need to have server 'backup' up-to-date with master3 before RESET MASTER, and remove domain id 20 from the gtid_slave_pos on backup after the RESET MASTER. So that is quite intrusive. - Kristian. _______________________________________________ Mailing list: https://launchpad.net/~maria-discuss Post to : maria-discuss@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-discuss More help : https://help.launchpad.net/ListHelp
