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MXS-1262: Move journal_max_age to MaxScale core

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The parameter is now defined in the monitor. Further refactoring is needed
to make the interface of the journal system simpler.
This commit is contained in:
Markus Mäkelä
2017-08-09 14:54:52 +03:00
parent 837d57f4f4
commit b448b129d0
8 changed files with 78 additions and 37 deletions
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27
Documentation/Monitors/Monitor-Common.md
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@ -115,3 +115,30 @@ lost_ndb |A MySQL Cluster node lost node membership
new_master |A new Master was detected
new_slave |A new Slave was detected
new_ndb |A new MySQL Cluster node was found
### `journal_max_age`
The maximum journal file age in seconds. The default value is 28800 seconds.
When the monitor starts, it reads any stored journal files. If the journal file
is older than the value of _journal_max_age_, it will be removed and the monitor
starts with no prior knowledge of the servers.
## Monitor Crash Safety
Starting with MaxScale 2.2.0, the monitor modules keep an on-disk journal of the
latest server states. This change makes the monitors crash-safe when options
that introduce states are used. It also allows the monitors to retain stateful
information when MaxScale is restarted.
For MySQL monitor, options that introduce states into the monitoring process are
the `detect_stale_master` and `detect_stale_slave` options, both of which are
enabled by default. Galeramon has the `disable_master_failback` parameter which
introduces a state.
The default location for the server state journal is in
`/var/lib/maxscale/<monitor name>/monitor.dat` where `<monitor name>` is the
name of the monitor section in the configuration file. If MaxScale crashes or is
shut down in an uncontrolled fashion, the journal will be read when MaxScale is
started. To skip the recovery process, manually delete the journal file before
starting MaxScale.

26
Documentation/Monitors/MySQL-Monitor.md
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@ -214,32 +214,6 @@ assigned the _Slave_ status which allows them to be used like normal slave
servers. When the option is disabled, the servers will only receive the _Slave
of External Server_ status and they will not be used.
### `journal_max_age`
The maximum journal file age in seconds. The default value is 28800 seconds.
When the MySQL monitor starts, it reads any stored journal files. If the journal
file is older than the value of _journal_max_age_, it will be removed and the
monitor starts with no prior knowledge of the servers.
## MySQL Monitor Crash Safety
Starting with MaxScale 2.2.0, the mysqlmon module keeps an on-disk journal of
the latest server states. This change makes the monitor crash-safe when options
that introduce states are used. It also allows the monitor to retain stateful
information when MaxScale is restarted.
Options that introduce states into the monitoring process are the
`detect_stale_master` and `detect_stale_slave` options, both of which are
enabled by default.
The default location for the server state journal is in
`/var/lib/maxscale/<monitor name>/mysqlmon.dat` where `<monitor name>` is the
name of the monitor section in the configuration file. If MaxScale crashes or is
shut down in an uncontrolled fashion, the journal will be read when MaxScale is
started. To skip the recovery process, manually delete the journal file before
starting MaxScale.
## Example 1 - Monitor script
Here is an example shell script which sends an email to an admin@my.org