# applied-index

Published articles for applied-index.

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## 【etcd】写入路径深读：Txn、mod revision 与 quota/alarm

DevFeed: [【etcd】写入路径深读：Txn、mod revision 与 quota/alarm](<https://devfeed.tech/articles/etcd-txn-mod-revision-quota-alarm-33989.md>)

Original publisher: [Read original article](<https://quant67.com/post/etcd/07-write-path/07-write-path.html>)

Author: Liao Tonglang

Published: 2026-08-26T00:00:00Z

Content type: tutorial

Language: zh

Sources: [土法炼钢 - 系统与基础设施](<https://devfeed.tech/sources/source-4.md>)

Topics: [etcd](<https://devfeed.tech/topics/etcd.md>), [Back end](<https://devfeed.tech/topics/backend.md>), [Raft](<https://devfeed.tech/topics/raft.md>), [Remote Procedure Call (RPC)](<https://devfeed.tech/topics/rpc.md>), [maintenance](<https://devfeed.tech/topics/maintenance.md>)

Tags: [alarm](<https://devfeed.tech/tags/alarm.md>), [apiserver](<https://devfeed.tech/tags/apiserver.md>), [applied-index](<https://devfeed.tech/tags/applied-index.md>), [apply](<https://devfeed.tech/tags/apply.md>), [batch](<https://devfeed.tech/tags/batch.md>), [bbolt](<https://devfeed.tech/tags/bbolt.md>), [committed-index](<https://devfeed.tech/tags/committed-index.md>), [compaction](<https://devfeed.tech/tags/compaction.md>), [defrag](<https://devfeed.tech/tags/defrag.md>), [distributed](<https://devfeed.tech/tags/distributed.md>), [errcompacted](<https://devfeed.tech/tags/errcompacted.md>), [etcd](<https://devfeed.tech/tags/etcd.md>), [follower](<https://devfeed.tech/tags/follower.md>), [k8s](<https://devfeed.tech/tags/k8s.md>), [kubernetes](<https://devfeed.tech/tags/kubernetes.md>), [mod-revision](<https://devfeed.tech/tags/mod-revision.md>), [nospace](<https://devfeed.tech/tags/nospace.md>), [quota](<https://devfeed.tech/tags/quota.md>), [revision](<https://devfeed.tech/tags/revision.md>), [txn](<https://devfeed.tech/tags/txn.md>), [v3-5](<https://devfeed.tech/tags/v3-5.md>), [v3-5-33](<https://devfeed.tech/tags/v3-5-33.md>)

### AI overview

This tutorial explains the etcd v3.5.33 write path from gRPC requests through Raft proposal, quota checks, MVCC apply, and ModRevision assignment. It also describes proposal backpressure, backend quota accounting, and how a NOSPACE alarm blocks writes while reads, deletes, and maintenance operations can continue.

### Source excerpt

走读 etcd v3.5.33 写入路径：raftRequest 背压、Txn compare/mod 与 ModRevision 分配、backend quota 与 NOSPACE alarm 如何把集群推入只读。

## 【etcd】WAL 与快照：预写日志、crash recovery 与 commit vs applied

DevFeed: [【etcd】WAL 与快照：预写日志、crash recovery 与 commit vs applied](<https://devfeed.tech/articles/etcd-wal-crash-recovery-commit-vs-applied-33985.md>)

Original publisher: [Read original article](<https://quant67.com/post/etcd/03-wal-snapshot/03-wal-snapshot.html>)

Author: Liao Tonglang

Published: 2026-08-26T00:00:00Z

Content type: tutorial

Language: zh

Sources: [土法炼钢 - 系统与基础设施](<https://devfeed.tech/sources/source-4.md>)

Topics: [etcd](<https://devfeed.tech/topics/etcd.md>), [Raft](<https://devfeed.tech/topics/raft.md>), [Kubernetes](<https://devfeed.tech/topics/kubernetes.md>)

Tags: [applied-index](<https://devfeed.tech/tags/applied-index.md>), [committed-index](<https://devfeed.tech/tags/committed-index.md>), [crash-recovery](<https://devfeed.tech/tags/crash-recovery.md>), [distributed](<https://devfeed.tech/tags/distributed.md>), [etcd](<https://devfeed.tech/tags/etcd.md>), [kubernetes](<https://devfeed.tech/tags/kubernetes.md>), [latency](<https://devfeed.tech/tags/latency.md>), [persistence](<https://devfeed.tech/tags/persistence.md>), [safety](<https://devfeed.tech/tags/safety.md>), [snapshot](<https://devfeed.tech/tags/snapshot.md>), [v3-5-33](<https://devfeed.tech/tags/v3-5-33.md>), [wal](<https://devfeed.tech/tags/wal.md>)

### AI overview

This tutorial explains how etcd v3.5.33 uses WAL segments and Raft snapshots for persistence, log compaction, and crash recovery. It also describes how committed and applied indexes can diverge, causing Watch delays or extended not-ready periods even when Raft replication appears healthy.

### Source excerpt

拆解 etcd v3.5.33 的 WAL 段文件、Raft snapshot 触发与重启 recovery 顺序；钉清 committed index 与 applied index 分叉对排障与 K8s 控制面的含义。

## 【etcd】treeIndex 与 Apply 管道：propose -\> commit -\> apply

DevFeed: [【etcd】treeIndex 与 Apply 管道：propose -\> commit -\> apply](<https://devfeed.tech/articles/etcd-treeindex-apply-propose-commit-apply-33988.md>)

Original publisher: [Read original article](<https://quant67.com/post/etcd/06-apply-pipeline/06-apply-pipeline.html>)

Author: Liao Tonglang

Published: 2026-08-26T00:00:00Z

Content type: tutorial

Language: zh

Sources: [土法炼钢 - 系统与基础设施](<https://devfeed.tech/sources/source-4.md>)

Topics: [etcd](<https://devfeed.tech/topics/etcd.md>), [Raft](<https://devfeed.tech/topics/raft.md>), [Back end](<https://devfeed.tech/topics/backend.md>)

Tags: [applied-index](<https://devfeed.tech/tags/applied-index.md>), [apply](<https://devfeed.tech/tags/apply.md>), [backend](<https://devfeed.tech/tags/backend.md>), [bbolt](<https://devfeed.tech/tags/bbolt.md>), [commit](<https://devfeed.tech/tags/commit.md>), [compaction](<https://devfeed.tech/tags/compaction.md>), [distributed](<https://devfeed.tech/tags/distributed.md>), [etcd](<https://devfeed.tech/tags/etcd.md>), [index](<https://devfeed.tech/tags/index.md>), [kubernetes](<https://devfeed.tech/tags/kubernetes.md>), [mvcc](<https://devfeed.tech/tags/mvcc.md>), [raft](<https://devfeed.tech/tags/raft.md>), [range](<https://devfeed.tech/tags/range.md>), [recovery](<https://devfeed.tech/tags/recovery.md>), [revision](<https://devfeed.tech/tags/revision.md>), [store](<https://devfeed.tech/tags/store.md>), [treeindex](<https://devfeed.tech/tags/treeindex.md>), [txn](<https://devfeed.tech/tags/txn.md>), [v3-5](<https://devfeed.tech/tags/v3-5.md>), [wal](<https://devfeed.tech/tags/wal.md>), [watch](<https://devfeed.tech/tags/watch.md>)

### AI overview

This tutorial explains the etcd v3.5.33 apply pipeline from Raft commit to MVCC application. It covers the separation between propose, commit, and apply; the roles of treeIndex and bbolt; consistent-index updates; watch notification timing; and troubleshooting committed-versus-applied lag.

### Source excerpt

走读 etcd v3.5.33 从 Raft commit 到 MVCC apply 的串行管道：treeIndex 与 bbolt 分工、consistent index、watchableStore 通知触发点，以及 committed/applied 分列排障。

## 【etcd】排障五轴：Raft/WAL/MVCC/Watch/Lease 口令表

DevFeed: [【etcd】排障五轴：Raft/WAL/MVCC/Watch/Lease 口令表](<https://devfeed.tech/articles/etcd-raft-wal-mvcc-watch-lease-33997.md>)

Original publisher: [Read original article](<https://quant67.com/post/etcd/15-troubleshoot/15-troubleshoot.html>)

Author: Liao Tonglang

Published: 2026-08-26T00:00:00Z

Content type: tutorial

Language: zh

Sources: [土法炼钢 - 系统与基础设施](<https://devfeed.tech/sources/source-4.md>)

Topics: [etcd](<https://devfeed.tech/topics/etcd.md>), [Kubernetes](<https://devfeed.tech/topics/kubernetes.md>)

Tags: [apiserver](<https://devfeed.tech/tags/apiserver.md>), [applied-index](<https://devfeed.tech/tags/applied-index.md>), [apply](<https://devfeed.tech/tags/apply.md>), [committed-index](<https://devfeed.tech/tags/committed-index.md>), [compaction](<https://devfeed.tech/tags/compaction.md>), [distributed](<https://devfeed.tech/tags/distributed.md>), [errcompacted](<https://devfeed.tech/tags/errcompacted.md>), [etcd](<https://devfeed.tech/tags/etcd.md>), [five-axes](<https://devfeed.tech/tags/five-axes.md>), [incident](<https://devfeed.tech/tags/incident.md>), [keepalive](<https://devfeed.tech/tags/keepalive.md>), [kubernetes](<https://devfeed.tech/tags/kubernetes.md>), [lag](<https://devfeed.tech/tags/lag.md>), [lease](<https://devfeed.tech/tags/lease.md>), [mvcc](<https://devfeed.tech/tags/mvcc.md>), [node-lease](<https://devfeed.tech/tags/node-lease.md>), [raft](<https://devfeed.tech/tags/raft.md>), [restore](<https://devfeed.tech/tags/restore.md>), [troubleshooting](<https://devfeed.tech/tags/troubleshooting.md>), [ttl](<https://devfeed.tech/tags/ttl.md>), [v3](<https://devfeed.tech/tags/v3.md>), [v3-5](<https://devfeed.tech/tags/v3-5.md>), [v3-5-33](<https://devfeed.tech/tags/v3-5-33.md>), [wal](<https://devfeed.tech/tags/wal.md>), [watch](<https://devfeed.tech/tags/watch.md>)

### AI overview

This troubleshooting article organizes etcd failures into five diagnostic axes: Raft consensus, WAL persistence and recovery, MVCC storage and capacity, Watch client synchronization, and Lease TTL semantics. It maps symptoms to axes, explains relevant etcdctl health and status fields, and notes Kubernetes control-plane relationships, including apiserver and Node Lease behavior. The article is anchored to etcd v3.5.33.

### Source excerpt

按 Raft、WAL、MVCC、Watch、Lease 五轴做症状否证；解释 etcdctl endpoint status/health 字段语义；并对照 K8s 控制面 apiserver 超时与 Node Lease 漂移。