Merge pull request #40817 from ahrtr/maintain_etcd_20230424

Add section “Maintaining etcd clusters” into “Operating etcd clusters for Kubernetes”

Author: k8s-ci-robot

content/en/docs/tasks/administer-cluster/configure-upgrade-etcd.md

@@ -394,3 +394,16 @@ For more details on etcd upgrade, please refer to the [etcd upgrades](https://et
 {{< note >}}
 Before you start an upgrade, please back up your etcd cluster first.
 {{< /note >}}
+
+## Maintaining etcd clusters
+
+Fore more details on etcd maintenance, please refer to the [etcd maintenance](https://etcd.io/docs/latest/op-guide/maintenance/) documentation.
+
+{{% thirdparty-content single="true" %}}
+
+{{< note >}}
+Defragmentation is an expensive operation, so it should be executed as infrequent
+as possible. On the other hand, it's also necessary to make sure any etcd member
+will not run out of the storage quota. The Kubernetes project recommends that when
+you perform defragmentation, you use a tool such as [etcd-defrag](https://github.com/ahrtr/etcd-defrag).
+{{< /note >}}