红帽全球峰会3.3. 磁盘延迟对 etcd 的影响
etcd 集群对磁盘延迟非常敏感。要了解 control plane 环境中 etcd 遇到的磁盘延迟，请运行 fio 测试或套件。
确保最终报告根据 etcd 对磁盘进行分类，如下例所示：
... 99th percentile of fsync is 5865472 ns 99th percentile of the fsync is within the recommended threshold: - 20 ms, the disk can be used to host etcd
...
99th percentile of fsync is 5865472 ns
99th percentile of the fsync is within the recommended threshold: - 20 ms, the disk can be used to host etcd当使用高延迟磁盘时，会出现一个信息说明磁盘不建议用于 etcd，如下例所示：
... 99th percentile of fsync is 15865472 ns 99th percentile of the fsync is greater than the recommended value which is 20 ms, faster disks are recommended to host etcd for better performance
...
99th percentile of fsync is 15865472 ns
99th percentile of the fsync is greater than the recommended value which is 20 ms, faster disks are recommended to host etcd for better performance当使用涵盖不满足推荐延迟的 etcd 磁盘的多个数据中心的集群部署时，它会增加服务影响失败的机会，并显著减少 control plane 可保持的网络延迟。
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