ETCD

Optimizing etcd on Slow Disks in Kubernetes In Kubernetes, etcd is the central database that stores the entire cluster state. If etcd runs on slow disks, you might notice performance issues: API requests slow down, pods take longer to schedule, and sometimes the cluster feels “laggy.” Why etcd Struggles on Slow Disks etcd is very I/O-intensive. Each write goes to disk to guarantee consistency. On spinning HDDs or cheap cloud disks with poor IOPS, etcd can quickly become a bottleneck. ...

ETCD ID Mismatch in Kubernetes ETCD is the key-value store used by Kubernetes to keep cluster state. Sometimes you may see the following error in ETCD logs: 2025-11-11 12:13:10.134330 E | rafthttp: request cluster ID mismatch (got fc5dec74b3dcf6fa want 4e38d7b9b94fe83c) It usually happens when a member of the ETCD cluster has a different ID than what the cluster expects. Causes Restoring a backup incorrectly. Copying ETCD data directories between nodes. Node reinstallation without cleaning old ETCD state. Cluster misconfiguration after scaling or failover. How to Fix Step 1: Identify the problem member ...

Introduction etcd is a distributed key-value store that plays a critical role in Kubernetes by storing cluster configuration and state. When etcd runs into problems, it can cause cluster instability or downtime. This article covers common etcd errors, their underlying causes, and actionable solutions. 1. etcdserver: request timed out ❓ Cause Occurs when etcd members can’t communicate efficiently, often due to network issues or disk I/O latency. 🛠️ Solution Check disk performance: iostat -xz 1 Ensure etcd data is on SSD storage. Check network latency and connectivity between cluster members: ping <etcd-member-IP> 2. etcdserver: leader changed ❓ Cause This is often seen when leadership changes too frequently, indicating instability in the etcd cluster. ...