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MXS-2011 Add documentation

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Johan Wikman 2018-09-03 19:32:08 +03:00
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Documentation/Routers/Binlogrouter.md
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@ -375,6 +375,65 @@ encryption_algorithm=aes_ctr
encryption_key_file=/var/binlogs/enc_key.txt
```
## Using secondary masters
From MaxScale 2.3 onwards it is possible to specify secondary masters that
the binlog router can use in case the connection to the default master fails.
**Note:** This is _only_ supported for gtid based replication in conjunction
with a Galera cluster.
The initial setup is performed exactly like when there is but one default master.
```
# mysql -h $MAXSCALE_HOST -P $MAXCALE_PORT
MariaDB> SET @@global.gtid_slave_pos='0-198-123';
MariaDB> CHANGE MASTER TO
MASTER_HOST='192.168.10.5',
MASTER_PORT=3306,
MASTER_USER='repl',
MASTER_PASSWORD='repl',
MASTER_USE_GTID=Slave_pos;
```
After the setup of the default master, secondary masters can be configured
as follows:
```
MariaDB> CHANGE MASTER ":2" TO
MASTER_HOST='192.168.10.6',
MASTER_PORT=3306,
MASTER_USER='repl',
MASTER_PASSWORD='repl',
MASTER_USE_GTID=Slave_pos;
```
That is, a connection name must be provided and the name must be of the
format `:N` where `N` is a positive integer. If several secondary masters
are specified, they must be numbered consecutively, starting from `2`.
All settings that are not explicitly specified are copied from the
default master. That is, the following is equivalent with the command
above:
```
MariaDB> CHANGE MASTER ":2" TO MASTER_HOST='192.168.10.6';
```
If a particular master configuration exists already, then any specified
definitions will be changed and unspecified ones will remain unchanged.
For instance, the following command would only change the password of `:2`.
```
MariaDB> CHANGE MASTER ":2" TO MASTER_PASSWORD='repl2';
```
It is not possible to delete a particular secondary master, but if
`MASTER_HOST` is set on the default master, even if it is set to the same
value, then _all_ secondary master configurations are deleted.
When `START SLAVE` is issued, MaxScale will first attempt to connect to the
default master and if that fails, try the secondary masters in order, until
a connection can be created. Only if all connection attempts fail, will
MaxScale wait as specified with `connect_retry`, before doing the cycle over
again.
Once the binlog router has successfully connected to a server, it will stay
connected to that server until the connection breaks or `STOP SLAVE` is
issued.
## Examples
The [Replication Proxy](../Tutorials/Replication-Proxy-Binlog-Router-Tutorial.md) tutorial will