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。
确保最终报告的磁盘状态适用于 etcd，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，会显示磁盘不推荐用于 etcd 的信息，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当使用跨多个数据中心的集群部署，且用于 etcd 的磁盘没有满足推荐的延迟要求，这会增加出现会影响服务的失败的机会，并会显著减少 control plane 在出现网络延迟时不影响正常工作的机会。
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