当我运行 sudo service MySQL start 时，我得到：
Job for mysql.service failed because the control process exited with error code. See "systemctl status mysql.service" and "journalctl -xe" for details.
当我跑步时journalctl -xe | tail -50我得到：
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit mysql.service has failed.
--
-- The result is failed.
Apr 30 10:55:58 servername systemd[1]: mysql.service: Unit entered failed state.
Apr 30 10:55:58 servername systemd[1]: mysql.service: Failed with result 'exit-code'.
Apr 30 10:55:58 servername systemd[1]: mysql.service: Service hold-off time over, scheduling restart.
Apr 30 10:55:58 servername systemd[1]: Stopped MySQL Community Server.
-- Subject: Unit mysql.service has finished shutting down
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit mysql.service has finished shutting down.
Apr 30 10:55:58 servername systemd[1]: Starting MySQL Community Server...
-- Subject: Unit mysql.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit mysql.service has begun starting up.
Apr 30 10:56:00 servername systemd[1]: mysql.service: Main process exited, code=exited, status=1/FAILURE
Apr 30 10:56:28 servername systemd[1]: Failed to start MySQL Community Server.
-- Subject: Unit mysql.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit mysql.service has failed.
--
-- The result is failed.
Apr 30 10:56:28 servername systemd[1]: mysql.service: Unit entered failed state.
Apr 30 10:56:28 servername systemd[1]: mysql.service: Failed with result 'exit-code'.
Apr 30 10:56:29 servername systemd[1]: mysql.service: Service hold-off time over, scheduling restart.
Apr 30 10:56:29 servername systemd[1]: Stopped MySQL Community Server.
-- Subject: Unit mysql.service has finished shutting down
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit mysql.service has finished shutting down.
Apr 30 10:56:29 servername systemd[1]: Starting MySQL Community Server...
-- Subject: Unit mysql.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit mysql.service has begun starting up.
Apr 30 10:56:30 servername sshd[12035]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=150.95.153.82 user=backup
Apr 30 10:56:31 servername systemd[1]: mysql.service: Main process exited, code=exited, status=1/FAILURE
Apr 30 10:56:33 servername sshd[12035]: Failed password for backup from 150.95.153.82 port 48284 ssh2
Apr 30 10:56:33 servername sshd[12035]: Received disconnect from 150.95.153.82 port 48284:11: Bye Bye [preauth]
Apr 30 10:56:33 servername sshd[12035]: Disconnected from 150.95.153.82 port 48284 [preauth]
我不确定是否ufw导致了此问题，当我运行时，sudo ufw status numbered我得到：
Status: active
To Action From
-- ------ ----
[ 1] 443 ALLOW IN Anywhere
[ 2] 80 ALLOW IN Anywhere
[ 3] 22 ALLOW IN 185.75.---
[ 4] 22 ALLOW IN 82.69.---
[ 5] 22 ALLOW IN 81.----
[ 6] 22 ALLOW IN Anywhere
[ 7] 22 ALLOW IN 185.----
[ 8] 873 ALLOW IN 185.----/24
[ 9] 3306 ALLOW IN 109.----/24
[10] 22 ALLOW IN 109.----/24
[11] 3306/tcp ALLOW IN Anywhere
[12] 3306 ALLOW IN Anywhere
[13] Anywhere ALLOW IN 185.2----
[14] 3306 ALLOW IN 185.2----
[15] 3306/tcp ALLOW OUT Anywhere (out)