Comment 0 for bug 1413560

I'm trying to backup a MariaDB server which is a slave (of a multi-source replication), however innobackupex doesn't detect it as such:

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150122 10:28:53 innobackupex: Continuing after ibbackup has suspended
innobackupex:: Not checking slave open temp tables for --safe-slave-backup because host is not a slave
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Looking at how the detection is done, I can understand why it says so:
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sub get_mysql_slave_status {
  mysql_query($_[0], "SHOW SLAVE STATUS");
}
...
   get_mysql_slave_status($con);

   if (defined($con->{slave_status}->{Read_Master_Log_Pos}) and
       defined($con->{slave_status}->{Slave_SQL_Running})) {
         $host_is_slave = 1;
   }
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Indeed, SHOW SLAVE STATUS has empty output on this server:

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MariaDB [(none)]> SHOW SLAVE STATUS;
Empty set (0.00 sec)
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This is because, on MariaDB >= 10.0.1, multi-source replication changes things a bit: https://mariadb.com/kb/en/mariadb/documentation/managing-mariadb/replication/standard-replication/multi-source-replication/

In particular, SHOW SLAVE STATUS only show a *default* replication, which is not mandatory to have.
You can in addition have others replications defined, all of which have a connection_name that you need to add to the command in order to have more info:

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MariaDB [(none)]> SHOW SLAVE 'instance7-XXXXXXXXX' STATUS\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
...
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You can also use the SHOW ALL SLAVES STATUS to have info on all the slaves defined:

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MariaDB [(none)]> show all slaves status\G
*************************** 1. row ***************************
              Connection_name: instance1-XXXXX
              Slave_SQL_State: Slave has read all relay log; waiting for the slave I/O thread to update it
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This surely has multiple implications for Xtrabackup to support this multi-source replication:
- Detection can be easy : checking server version, using SHOW ALL SLAVE STATUS to detect multi-source replication and acting as such.
- Stopping / restarting slave(s) needs to be enhanced to iterate on all active slave(s) connections.
- The CHANGE MASTER commands may also need to be handled (may be differently if the connection is in GTID or non-GTID mode)
There may also be other implications that I did not thought of.

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$ cat /etc/redhat-release
CentOS release 6.6 (Final)
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$ rpm -q percona-xtrabackup
percona-xtrabackup-2.2.8-5059.el6.x86_64
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$ innobackupex --version
InnoDB Backup Utility v1.5.1-xtrabackup; Copyright 2003, 2009 Innobase Oy
and Percona LLC and/or its affiliates 2009-2013. All Rights Reserved.
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$ xtrabackup --version
xtrabackup version 2.2.8 based on MySQL server 5.6.22 Linux (x86_64) (revision id: )
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$ mysql --version
mysql Ver 15.1 Distrib 10.0.15-MariaDB, for Linux (x86_64) using readline 5.1
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