前置文章：
- windows通用网线连接ubuntu实现ssh登录、桌面控制、文件共享
- Ubuntu挂载HDD迁移存储PostgreSQL数据
背景：
启动实体Ubuntu机器后后很大的概率PostgreSQL不会成功启动，查看日志：
Ubuntu启动时间：
root@Pine-Tree:~# uptime -s
2025-04-19 09:52:24
查看PostgreSQL运行状态
root@Pine-Tree:~# sudo systemctl status postgresql@15-main
× postgresql@15-main.service - PostgreSQL Cluster 15-mainLoaded: loaded (/lib/systemd/system/postgresql@.service; enabled; vendor preset: enabled)Active: failed (Result: protocol) since Sat 2025-04-19 09:52:26 CST; 15min agoProcess: 700 ExecStart=/usr/bin/pg_ctlcluster --skip-systemctl-redirect 15-main start (code=exited, status=1/FAILURE)CPU: 41ms4月 19 09:52:26 Pine-Tree systemd[1]: Starting PostgreSQL Cluster 15-main...
4月 19 09:52:26 Pine-Tree postgresql@15-main[700]: Error: /mnt/pgdata/main is not accessible or does not exist
4月 19 09:52:26 Pine-Tree systemd[1]: postgresql@15-main.service: Can't open PID file /run/postgresql/15-main.pid (yet?) after start: Operation not permitted
4月 19 09:52:26 Pine-Tree systemd[1]: postgresql@15-main.service: Failed with result 'protocol'.
4月 19 09:52:26 Pine-Tree systemd[1]: Failed to start PostgreSQL Cluster 15-main.可知在系统启动2秒后就开始尝试启动PostgreSQL了，但是挂载目录/mnt/pgdata/main还无法访问，导致PostgreSQL启动失败。
查询相关资料发现冷启动HDD通过USB3.0连接从开机到系统检测完毕大概需要3-20秒 。
解决思路：
使用systemctl edit调整启动策略
方案一、设置PostgreSQL延迟5秒启动
创建文件夹用于systemctl edit配置
sudo mkdir -p /etc/systemd/system/postgresql@15-main.service.d
新增片段覆盖文件
sudo nano /etc/systemd/system/postgresql@15-main.service.d/override.conf
在打开的编辑器中添加以下内容
[Service]
ExecStartPre=/bin/sleep 5
保存并退出，然后重新加载systemd配置
sudo systemctl daemon-reload
重新启动验证
reboot
确认PostgreSQL运行状况
启动成功：
root@Pine-Tree:~# sudo systemctl status postgresql@15-main
● postgresql@15-main.service - PostgreSQL Cluster 15-mainLoaded: loaded (/lib/systemd/system/postgresql@.service; enabled; vendor preset: enabled)Drop-In: /etc/systemd/system/postgresql@15-main.service.d└─override.confActive: active (running) since Sat 2025-04-19 11:20:15 CST; 2min 14s agoProcess: 814 ExecStartPre=/bin/sleep 5 (code=exited, status=0/SUCCESS)Process: 1440 ExecStart=/usr/bin/pg_ctlcluster --skip-systemctl-redirect 15-main start (code=exited, status=0/SUCCESS)Main PID: 1446 (postgres)
Ubuntu启动时间：
root@Pine-Tree:~# uptime -s
2025-04-19 11:19:56
确认PostgreSQL启动时间，可知延迟启动生效
root@Pine-Tree:~# ps -eo pid,lstart,cmd | grep postgres | grep -v grep1446 Sat Apr 19 11:20:05 2025 /usr/lib/postgresql/15/bin/postgres -D /mnt/pgdata/main -c config_file=/etc/postgresql/15/main/postgresql.conf1483 Sat Apr 19 11:20:08 2025 postgres: 15/main: checkpointer 1484 Sat Apr 19 11:20:08 2025 postgres: 15/main: background writer 1486 Sat Apr 19 11:20:10 2025 postgres: 15/main: walwriter 1487 Sat Apr 19 11:20:10 2025 postgres: 15/main: autovacuum launcher 1488 Sat Apr 19 11:20:10 2025 postgres: 15/main: logical replication launcher 1838 Sat Apr 19 11:22:32 2025 postgres: 15/main: postgres dbname 192.168.125.2(6139) idle方案二、PostgreSQL开机自启动失败后重试2次（间隔10秒）
修改override.conf
sudo nano /etc/systemd/system/postgresql@15-main.service.d/override.conf
配置调整为：
[Service]
Restart=on-failure
RestartSec=10s
StartLimitBurst=2
保存并退出，然后重新加载systemd配置
sudo systemctl daemon-reload
重新启动验证
reboot
确认PostgreSQL运行状况
启动成功：
root@Pine-Tree:~# sudo systemctl status postgresql@15-main
● postgresql@15-main.service - PostgreSQL Cluster 15-mainLoaded: loaded (/lib/systemd/system/postgresql@.service; enabled; vendor preset: enabled)Drop-In: /etc/systemd/system/postgresql@15-main.service.d└─override.confActive: active (running) since Sat 2025-04-19 12:30:06 CST; 7min agoProcess: 1479 ExecStart=/usr/bin/pg_ctlcluster --skip-systemctl-redirect 15-main start (code=exited, status=0/SUCCESS)Main PID: 1487 (postgres)
Ubuntu启动时间：
root@Pine-Tree:~# uptime -s
2025-04-19 12:29:47
查看PostgreSQL历史启动记录，可知12:29:50s首次启动PostgreSQL失败，10秒过后启动成功：
root@Pine-Tree:~# sudo journalctl -u postgresql@15-main --no-pager -n 50-- Boot 0ba0937613c14ba8b47c6bb17de28bcd --
4月 19 12:29:50 Pine-Tree systemd[1]: Starting PostgreSQL Cluster 15-main...
4月 19 12:29:50 Pine-Tree postgresql@15-main[794]: Error: /mnt/pgdata/main is not accessible or does not exist
4月 19 12:29:50 Pine-Tree systemd[1]: postgresql@15-main.service: Can't open PID file /run/postgresql/15-main.pid (yet?) after start: Operation not permitted
4月 19 12:29:50 Pine-Tree systemd[1]: postgresql@15-main.service: Failed with result 'protocol'.
4月 19 12:29:50 Pine-Tree systemd[1]: Failed to start PostgreSQL Cluster 15-main.
4月 19 12:30:00 Pine-Tree systemd[1]: postgresql@15-main.service: Scheduled restart job, restart counter is at 1.
4月 19 12:30:00 Pine-Tree systemd[1]: Stopped PostgreSQL Cluster 15-main.
4月 19 12:30:00 Pine-Tree systemd[1]: Starting PostgreSQL Cluster 15-main...
4月 19 12:30:06 Pine-Tree systemd[1]: Started PostgreSQL Cluster 15-main.
方案三、设置PostgreSQL延迟5秒启动同时设置启动失败后重试2次（间隔10秒 ）
修改override.conf后重新验证
sudo nano /etc/systemd/system/postgresql@15-main.service.d/override.conf
配置调整为：
[Service]
ExecStartPre=/bin/sleep 5
Restart=on-failure
RestartSec=10s
StartLimitBurst=2
保存并退出，然后重新加载systemd配置
大部分情况下，延迟5秒即可保证启动成功，不会走到重试逻辑
sudo systemctl daemon-reload
问题汇总
sudo systemctl edit postgresql@15-main编辑后保存失败，提示文件不存在
root@Pine-Tree:~# sudo systemctl edit postgresql@15-main
Editing "/etc/systemd/system/postgresql@15-main.service.d/override.conf" canceled: temporary file is empty.
解决措施：
创建文件夹用于systemctl edit配置
sudo mkdir -p /etc/systemd/system/postgresql@15-main.service.d
新增片段覆盖文件，然后编辑
sudo nano /etc/systemd/system/postgresql@15-main.service.d/override.conf
