High Availability in WQ-RDS with Zero Data Loss

3rd chunk of `content/en/blog/_posts/2018-03-00-How-To-Integrate-Rollingupdate-Strategy.md`

977f4ade89d09d4d4ce3451c275346903b9c520a6886e3710000000100000592

[root@k8s-master ~]# kubectl get mysqldatabase  

NAME KIND  

clustershard-c0 MysqlDatabase.v1.mysql.orain.com  

clustershard-c1 MysqlDatabase.v1.mysql.orain.com  

clustershard-c2 MysqlDatabase.v1.mysql.orain.com  

clustershard-c3 MysqlDatabase.v1.mysql.orain.com  

clustershard-c4 MysqlDatabase.v1.mysql.orain.com  

clustershard-c5 MysqlDatabase.v1.mysql.orain.com  

clustershard-c6 MysqlDatabase.v1.mysql.orain.com  

clustershard-c7 MysqlDatabase.v1.mysql.orain.com
```


Next, let's look at two main features: high availability and RollingUpdate strategy.

To demonstrate, we'll start by running sysbench to generate some load on the cluster. In this example, QPS metrics are generated by MySQL export, collected by Prometheus, and visualized in Grafana.

###  Feature: high availability

WQ-RDS handles MySQL instance crashes while protecting against data loss.

When killing clustershard-c0, WQ-RDS will detect that clustershard-c0 is unavailable and replace clustershard-c0 on failed machine, taking about 35 seconds on average.

![](https://lh3.googleusercontent.com/sXqVqfTu6rMWn0mlHLgHHqATe_qsx1tNmMfX60HoTwyhd5HCL4A_ViFBQAZfOoVGioeXcI_XXbzVFUdq2hbKGwS0OXH6PFGqgpZshfBwrT088bz4KqeyTbHpQR2olyzE6eRo1fan)

zero data loss at same time.

![](https://lh6.googleusercontent.com/7xnN_sODa-3Ch3ScAUlggCTeYfnE3-wxRaCIHrljHCB7LnXgth8zeCv0gk_UU1jbSDBQuACQ2Mf1FO1-E7GvMWwGKjp7irenAKp4DkHlA5LR9OVuLXqubPFhhksA8kfBUh4Z4OuN)

Title: High Availability in WQ-RDS with Zero Data Loss

Summary

This section highlights the high availability feature of WQ-RDS. It shows how WQ-RDS handles MySQL instance crashes, specifically mentioning the automatic detection and replacement of a failed instance (clustershard-c0). The recovery process takes approximately 35 seconds, ensuring zero data loss. The section includes visualizations to demonstrate this capability.