# RKE2 etcd 分開 wal-dir & data-dir 目錄
* data-dir 是 etcd 的數據目錄，用於存放所有的持久化數據，包括數據快照。
* WAL 文件：記錄了對數據的所有變更操作，就是 ETCD 的 log。
* 可以透過 `--wal-dir` 參數來指定 WAL 的存放目錄，在性能敏感或數據可靠性要求極高的情境下，分離 wal-dir 是推薦的做法，但需注意配置一致性和存儲設備的性能。如果未配置 wal-dir，預寫日誌將存儲在 data-dir 中。


    machineGlobalConfig:
      cni: calico
      disable-kube-proxy: false
      etcd-arg:
        - data-dir=/etcd/data
        - wal-dir=/etcd/wal
      etcd-expose-metrics: false
      etcd-extra-mount:
        - /etcd:/etcd

* 驗證

$ ls -l /etcd
total 0
drwx------ 1 root root 12 Jan 10 10:43 data
drwx------ 1 root root 84 Jan 10 10:43 wal

$ cat /etc/rancher/rke2/config.yaml.d/50-rancher.yaml
{
  "agent-token": "d7qb9frh5xm2mv7c472gjsl94gk2gvtw8w9cjj2nt75mmqfnvfw78m",
  "cni": "calico",
  "disable-kube-proxy": false,
  "etcd-arg": [
    "data-dir=/etcd/data",
    "wal-dir=/etcd/wal"
  ],
  "etcd-expose-metrics": false,
  "etcd-extra-mount": [
    "/etcd:/etcd"
  ],
......

$ cat /var/lib/rancher/rke2/server/db/etcd/config
advertise-client-urls: https://192.168.11.70:2379
auto-compaction-mode: periodic
auto-compaction-retention: 1h0m0s
client-transport-security:
  cert-file: /var/lib/rancher/rke2/server/tls/etcd/server-client.crt
  client-cert-auth: true
  key-file: /var/lib/rancher/rke2/server/tls/etcd/server-client.key
  trusted-ca-file: /var/lib/rancher/rke2/server/tls/etcd/server-ca.crt
data-dir: /etcd/data
election-timeout: 5000
experimental-initial-corrupt-check: true
experimental-watch-progress-notify-interval: 5000000000
heartbeat-interval: 500
initial-advertise-peer-urls: https://192.168.11.70:2380
initial-cluster: rke2-72c87363=https://192.168.11.70:2380
initial-cluster-state: new
listen-client-http-urls: https://127.0.0.1:2382
listen-client-urls: https://127.0.0.1:2379,https://192.168.11.70:2379
listen-metrics-urls: http://127.0.0.1:2381
listen-peer-urls: https://127.0.0.1:2380,https://192.168.11.70:2380
log-outputs:
- stderr
logger: zap
name: rke2-72c87363
peer-transport-security:
  cert-file: /var/lib/rancher/rke2/server/tls/etcd/peer-server-client.crt
  client-cert-auth: true
  key-file: /var/lib/rancher/rke2/server/tls/etcd/peer-server-client.key
  trusted-ca-file: /var/lib/rancher/rke2/server/tls/etcd/peer-ca.crt
quota-backend-bytes: '''6442450944'''
snapshot-count: 10000
wal-dir: /etcd/wal

## 參考

https://etcd.io/docs/v3.4/op-guide/configuration/#:~:text=This%20allows%20a%20dedicated%20disk%20to%20be%20used%2C%20and%20helps%20avoid%20io%20competition%20between%20logging%20and%20other%20IO%20operations