几天前（8 月 18 日），一位朋友意外地在管理面板中重启了他的 VPS（VPS 主机是 OVH）。问题是……它从未重启过。他几个月没有在他的 VPS 上做任何更改，该 VPS 运行的是Plesk面板CentOS 6。
救援启动（从实时 CD 启动）效果很好。我可以挂载分区并查看所有数据。我尝试寻找提示，/var/log但有自 8 月 18 日以来无日志。今天我尝试重启它时没有任何记录。
输出tail -n 20 /var/log/messages：
Aug 18 11:28:21 vpsXXXXXX proftpd[11413]: XXX.XXX.XXX.XXX (YYY.YYY.YYY.YYY[YYY.YYY.YYY.YYY]) - FTP session opened.
Aug 18 11:29:22 vpsXXXXXX proftpd[11413]: XXX.XXX.XXX.XXX (YYY.YYY.YYY.YYY[YYY.YYY.YYY.YYY]) - FTP session closed.
Aug 18 11:29:22 vpsXXXXXX xinetd[1020]: EXIT: ftp status=0 pid=11413 duration=61(sec)
Aug 18 11:38:09 vpsXXXXXX init: tty (/dev/tty1) main process (2901) killed by TERM signal
Aug 18 11:38:09 vpsXXXXXX init: serial (ttyS0) main process (2902) killed by TERM signal
Aug 18 11:38:11 vpsXXXXXX xinetd[1020]: Exiting...
Aug 18 11:38:11 vpsXXXXXX acpid: exiting
Aug 18 11:38:11 vpsXXXXXX init: Disconnected from system bus
Aug 18 11:38:11 vpsXXXXXX console-kit-daemon[30927]: WARNING: no sender#012
Aug 18 11:38:11 vpsXXXXXX named[376]: received control channel command 'stop'
Aug 18 11:38:11 vpsXXXXXX named[376]: shutting down: flushing changes
Aug 18 11:38:11 vpsXXXXXX named[376]: stopping command channel on 127.0.0.1#953
Aug 18 11:38:11 vpsXXXXXX named[376]: no longer listening on 127.0.0.1#53
Aug 18 11:38:11 vpsXXXXXX named[376]: no longer listening on XXX.XXX.XXX.XXX#53
Aug 18 11:38:11 vpsXXXXXX named[376]: exiting
Aug 18 11:38:11 vpsXXXXXX auditd[817]: The audit daemon is exiting.
Aug 18 11:38:11 vpsXXXXXX kernel: type=1305 audit(1503049091.989:89): audit_pid=0 old=817 auid=4294967295 ses=4294967295 res=1
Aug 18 11:38:12 vpsXXXXXX kernel: type=1305 audit(1503049092.089:90): audit_enabled=0 old=1 auid=4294967295 ses=4294967295 res=1
Aug 18 11:38:12 vpsXXXXXX kernel: Kernel logging (proc) stopped.
Aug 18 11:38:12 vpsXXXXXX rsyslogd: [origin software="rsyslogd" swVersion="5.8.10" x-pid="847" x-info="http://www.rsyslog.com"] exiting on signal 15.
输出cat /var/log/boot.log：
Welcome to CentOS
Starting udev: udevd[306]: can not read '/etc/udev/rules.d/75-persistent-net-generator.rules'
udevd[306]: can not read '/etc/udev/rules.d/75-persistent-net-generator.rules'
[ OK ]
Setting hostname vpsXXXXXX.ovh.net: [ OK ]
Checking filesystems
Checking all file systems.
[/sbin/fsck.ext4 (1) -- /] fsck.ext4 -a /dev/vda1
/dev/vda1: clean, 244942/1638400 files, 6238128/6553344 blocks
[ OK ]
Remounting root filesystem in read-write mode: [ OK ]
Mounting local filesystems: [ OK ]
ln: creating symbolic link `/dev/root': File exists
Enabling /etc/fstab swaps: [ OK ]
Entering non-interactive startup
ip6tables: Applying firewall rules: [ OK ]
iptables: Applying firewall rules: [ OK ]
Bringing up loopback interface: [ OK ]
Bringing up interface eth0:
Determining IP information for eth0... done.
[ OK ]
Starting auditd: [ OK ]
Starting portreserve: [ OK ]
Starting system logger: [ OK ]
Starting Dr.Web drwebd...
Dr.Web (R) daemon for Linux/Plesk Edition v6.0.2.1
Copyright (c) Igor Daniloff, 1992-2017
Doctor Web, Moscow, Russia
Support service: http://support.drweb.com
To purchase: http://buy.drweb.com
Key file: /opt/drweb/drweb32.key - Key file was not found! (No such file or directory)
A path to a valid license key file was not specified.
Plesk authorization failed: HTTP request error [7]
Error: Plesk Software not running.
Starting kdump:[ OK ]
Starting system message bus: [ OK ]
Mounting filesystems: [ OK ]
Starting acpi daemon: [ OK ]
Retrigger failed udev events[ OK ]
Starting sshd: [ OK ]
Starting xinetd: [ OK ]
Starting Courier IMAP authentication daemon: [ OK ]
Starting Courier IMAP server: [ OK ]
Starting Courier IMAP server with SSL/TLS support: [ OK ]
Starting Courier POP3 server: [ OK ]
Starting Courier POP3 server with SSL/TLS support: [ OK ]
Starting psa-pc-remote: [ OK ]
Starting php-fpm: [18-Aug-2017 11:16:04] WARNING: Nothing matches the include pattern '/opt/plesk/php/5.6/etc/php-fpm.d/*.conf' from /opt/plesk/php/5.6/etc/php-fpm.conf at line 119.
[18-Aug-2017 11:16:04] ERROR: No pool defined. at least one pool section must be specified in config file
[18-Aug-2017 11:16:04] ERROR: failed to post process the configuration
[18-Aug-2017 11:16:04] ERROR: FPM initialization failed
[FAILED]
Starting psa... Starting sw-engine-fpm: [ OK ]
done
Starting xinetd service... done
Starting sw-cp-server service... done
Starting mysqld service... failed
Trying to connect to MySQL... Failed to connect to MySQL: ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
Trying to start service mysqld... mysqld dead but pid file exists
Timeout error occurred trying to start MySQL Daemon.
Starting mysqld: [FAILED]
WARNING!
Some problems are found during start(see log file: /var/log/plesk/install/plesk_12.0.18_reset_instance_data.log)
Continue...
Trying to start service mysqld... mysqld dead but pid file exists
Timeout error occurred trying to start MySQL Daemon.
Starting mysqld: [FAILED]
WARNING!
Some problems are found during start(see log file: /var/log/plesk/install/plesk_12.0.18_reset_instance_data.log)
Continue...
Trying to establish test connection... ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (111)
ERROR 2013 (HY000): Lost connection to MySQL server at 'reading initial communication packet', system error: 104
failed
ERROR while trying to establish test connection
Check the error reason(see log file: /var/log/plesk/install/plesk_12.0.18_reset_instance_data.log), fix and try again
Starting named service... done
Starting postgresql service... not installed
Starting spamassassin service... not installed
Plesk: Starting Mail Server... done
Starting psa... Starting sw-engine-fpm:
done
Starting sw-engine-fpm:
Starting nginx: [ OK ]
Starting crond: [ OK ]
initctl: Event failed
在这种机器启动时您无法在屏幕上看到潜在错误的情况下，您如何诊断和修复此类问题？