hcq/MaxScale
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Added galeramon server priorities.

Browse Source
This commit is contained in:
Markus Makela
2015-07-13 14:39:04 +03:00
parent 4276983d6f
commit 19fe7127d5
3 changed files with 38 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
Documentation/monitors/Galera-Monitor.md
View File

@ -98,9 +98,17 @@ A list of event names which cause the script to be executed. If this option is n
events=master_down,slave_down
```
### `use_priority`
Enable interaction with server priorities. This will allow the monitor to deterministically pick the write node for the monitored Galera cluster and will allow for controlled node replacement.
```
use_priority=true
```
## Interaction with Server Priorities
If a server is configured with the `priority=<int>` parameter, galeramon will use that as the basis on which the master node is chosen. This requires the `disable_master_role_setting` to be undefined or disabled. The server with the lowest value in `priority` will be chosen as the master node when a replacement Galera node is promoted to a master server inside MaxScale.
If the `use_priority` option is set and a server is configured with the `priority=<int>` parameter, galeramon will use that as the basis on which the master node is chosen. This requires the `disable_master_role_setting` to be undefined or disabled. The server with the lowest value in `priority` will be chosen as the master node when a replacement Galera node is promoted to a master server inside MaxScale.
Here is an example with two servers.
@ -119,12 +127,14 @@ priority=3
[node-3]
type=server
address=192.168.122.102
address=192.168.122.103
port=3306
priority=2
```
This will use `node-1` as the master if available and `node-3` if the first one isn't available. `node-2` will only be used as the master if both `node-1` and `node-3` are down.
In this example `node-1` is always used as the master if available. If `node-1` is not available, then the next node with the highest priority rank is used. In this case it would be `node-3`. If both `node-1` and `node-3` were down, then `node-2` would be used. Nodes without priority are considered as having the lowest priority rank and will be used only if all nodes with priority ranks are not available.
With priority ranks you can control the order in which MaxScale chooses the master node. This will allow for a controlled failure and replacement of nodes.
## Script events