MySQL啟動故障處理一例（errno13）
之前在系統上裝了個MySQL用於測試，今天發現啟動mysqld_safe進程的時候報錯,如下所示：
[root@bak local]# mysqld_safe &
[1] 2631
[root@bak local]# Starting mysqld daemon with databases from /data/mysql/mysql_3306/data
STOPPING server from pid file /data/mysql/mysql_3306/data/bak.pid
141017 09:20:23 mysqld ended
[1]+ Done mysqld_safe
由於我的my.cnf並沒有改名，使用的是默認的/etc/my.cnf這個位置，因此mysqld_safe &可以不用指定任何參數，需要的參數已經在my.cnf中指定了，如果使用的my.cnf位置不在/etc/下面，或者改過了自定義的名字，那麼需要用--defaults-file參數來指定my.cnf文件的位置
[root@bak local]# cd /data/mysql/mysql_3306/logs/
[root@bak logs]# ll
total 0
查看日志，並沒有任何binlog生成，這裡說明一下，這個環境是從原來的一台主機上clone過來的，clone完以後沒有啟動過MySQL,我想可能是因為這個緣故
[root@bak mysql_3306]# cd /usr/local
[root@bak local]# chown -R mysql:mysql /data/mysql/
[root@bak local]# chown -R mysql:mysql /usr/local/mysql/
[root@bak local]# ll
total 76
drwxr-xr-x 2 mysql 502 4096 Aug 25 11:39 bin
-rw-rw---- 1 mysql root 432 Oct 17 09:20 error.log
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 etc
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 games
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 include
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 lib
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 libexec
lrwxrwxrwx 1 root root 38 Sep 24 00:12 mysql -> /opt/mysql/mysql-5.5.39-linux2.6-i686/
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 sbin
drwxr-xr-x 5 mysql 502 4096 Aug 25 11:39 share
drwxr-xr-x 2 mysql 502 4096 Sep 23 20:34 src
[root@bak local]# id mysql
uid=501(mysql) gid=1000(mysql) groups=1000(mysql)
mysql用戶id為501，但不知為何顯示的是mysql 502的形式，而不是mysql mysql
開始以為是因為/usr/local/mysql這個目錄是root:root的緣故，但改為mysql:mysql後，依然無法啟動
[root@bak data]# chown -R mysql:mysql /usr/local
[root@bak data]# cd /usr/local
[root@bak local]# ll
total 76
drwxr-xr-x 2 mysql 502 4096 Aug 25 11:39 bin
-rw-rw---- 1 mysql root 432 Oct 17 09:20 error.log
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 etc
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 games
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 include
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 lib
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 libexec
lrwxrwxrwx 1 mysql mysql 38 Sep 24 00:12 mysql -> /opt/mysql/mysql-5.5.39-linux2.6-i686/
drwxr-xr-x 2 mysql 502 4096 Aug 8 2008 sbin
drwxr-xr-x 5 mysql 502 4096 Aug 25 11:39 share
drwxr-xr-x 2 mysql 502 4096 Sep 23 20:34 src
[root@bak local]# mysqld_safe &
[1] 2692
[root@bak local]# Starting mysqld daemon with databases from /data/mysql/mysql_3306/data
[root@bak local]# mysql
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
報了一個無法通過socket連接到服務器，於是想是不是應該在client項目中添加socket=/tmp/mysql.sock這個參數
--先查看下原來有的配置
[root@bak local]# cat /etc/my.cnf
[client]
port = 3306
socket = /tmp/mysql.sock
[mysqld_safe]
open_files_limit = 8192
user = mysql
log-error = error.log
...省略以下部分
看來client總已經指定了socket，應該不是這個問題，要判斷問題出在哪裡，最直接都就是查看error.log文件，由於我在my.cnf參數中指定了error.log的位置，放在了數據文件目錄下，並更改了名字。如果沒有改，默認的名字為<host_name>.error
[root@bak local]# cat /data/mysql/mysql_3306/data/error.log
141017 9:24:53 [Warning] Using unique option prefix myisam_recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use
the full name instead.
141017 9:24:53 [Note] Plugin 'FEDERATED' is disabled.
/usr/libexec/mysqld: Table 'mysql.plugin' doesn't exist
141017 9:24:53 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
141017 9:24:53 InnoDB: The InnoDB memory heap is disabled
141017 9:24:53 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
141017 9:24:53 InnoDB: Compressed tables use zlib 1.2.3
141017 9:24:53 InnoDB: Using Linux native AIO
141017 9:24:53 InnoDB: Initializing buffer pool, size = 128.0M
141017 9:24:53 InnoDB: Completed initialization of buffer pool
InnoDB: The first specified data file ./ibdata1 did not exist:
InnoDB: a new database to be created!
141017 9:24:53 InnoDB: Setting file ./ibdata1 size to 100 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Progress in MB: 100
141017 9:24:58 InnoDB: Log file ./ib_logfile0 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile0 size to 100 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Progress in MB: 100
141017 9:25:03 InnoDB: Log file ./ib_logfile1 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile1 size to 100 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Progress in MB: 100
141017 9:25:08 InnoDB: Log file ./ib_logfile2 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile2 size to 100 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Progress in MB: 100
InnoDB: Doublewrite buffer not found: creating new
InnoDB: Doublewrite buffer created
InnoDB: 127 rollback segment(s) active.
InnoDB: Creating foreign key constraint system tables
InnoDB: Foreign key constraint system tables created
141017 9:25:13 InnoDB: Waiting for the background threads to start
141017 9:25:14 InnoDB: 5.5.39 started; log sequence number 0
141017 9:25:14 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306
141017 9:25:14 [Note] - '0.0.0.0' resolves to '0.0.0.0';
141017 9:25:14 [Note] Server socket created on IP: '0.0.0.0'.
141017 9:25:14 [ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist
141017 9:26:15 [Warning] Using unique option prefix myisam_recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
141017 9:26:15 [Note] Plugin 'FEDERATED' is disabled.
/usr/libexec/mysqld: Table 'mysql.plugin' doesn't exist
141017 9:26:15 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
141017 9:26:15 InnoDB: The InnoDB memory heap is disabled
141017 9:26:15 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
141017 9:26:15 InnoDB: Compressed tables use zlib 1.2.3
141017 9:26:15 InnoDB: Using Linux native AIO
141017 9:26:15 InnoDB: Initializing buffer pool, size = 128.0M
141017 9:26:15 InnoDB: Completed initialization of buffer pool
141017 9:26:15 InnoDB: highest supported file format is Barracuda.
InnoDB: Log scan progressed past the checkpoint lsn 48941
141017 9:26:15 InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages from the doublewrite
InnoDB: buffer...
InnoDB: Doing recovery: scanned up to log sequence number 1595668
141017 9:26:15 InnoDB: Starting an apply batch of log records to the database...
InnoDB: Progress in percents: 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72
73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
InnoDB: Apply batch completed
141017 9:26:15 InnoDB: Waiting for the background threads to start
141017 9:26:16 InnoDB: 5.5.39 started; log sequence number 1595668
141017 9:26:16 [Note] Recovering after a crash using /data/mysql/mysql_3306/logs/mysql-bin
141017 9:26:16 [Note] Starting crash recovery...
141017 9:26:16 [Note] Crash recovery finished.
141017 9:26:17 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306
141017 9:26:17 [Note] - '0.0.0.0' resolves to '0.0.0.0';
141017 9:26:17 [Note] Server socket created on IP: '0.0.0.0'.
141017 9:26:17 [ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist
日志中報錯提示無法打開mysql.plugin表，也不存在mysql.host這張表，由於是測試環境，沒有什麼數據，於是決定重新初始化MySQL
[root@bak local]# cd mysql
[root@bak mysql]# ./scripts/mysql_install_db
Installing MySQL system tables...
141017 9:28:24 [Warning] options --log-slow-admin-statements, --log-queries-not-using-indexes and --log-slow-slave-statements have no effect if --log_slow_queries is not set
OK
Filling help tables...
141017 9:28:25 [Warning] options --log-slow-admin-statements, --log-queries-not-using-indexes and --log-slow-slave-statements have no effect if --log_slow_queries is not set
OK
To start mysqld at boot time you have to copy
support-files/mysql.server to the right place for your system
PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER !
To do so, start the server, then issue the following commands:
/usr/local/mysql/bin/mysqladmin -u root password 'new-password'
/usr/local/mysql/bin/mysqladmin -u root -h bak password 'new-password'
Alternatively you can run:
/usr/local/mysql/bin/mysql_secure_installation
which will also give you the option of removing the test
databases and anonymous user created by default. This is
strongly recommended for production servers.
See the manual for more instructions.
You can start the MySQL daemon with:
cd /usr/local/mysql ; /usr/local/mysql/bin/mysqld_safe &
You can test the MySQL daemon with mysql-test-run.pl
cd /usr/local/mysql/mysql-test ; perl mysql-test-run.pl
Please report any problems at http://bugs.mysql.com/
[root@bak mysql]# mysqld_safe &
[1] 2858
[root@bak mysql]# Starting mysqld daemon with databases from /data/mysql/mysql_3306/data
[root@bak mysql]# mysqSTOPPING server from pid file /data/mysql/mysql_3306/data/bak.pid
l141017 09:28:36 mysqld ended
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
[1]+ Done mysqld_safe
初始化時成功的，可以看到有2個OK，不過啟動依然報錯，再次查看error.log
[root@bak mysql]# cat /data/mysql/mysql_3306/data/error.log
141017 9:24:53 [Warning] Using unique option prefix myisam_recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
141017 9:24:53 [Note] Plugin 'FEDERATED' is disabled.
/usr/libexec/mysqld: Table 'mysql.plugin' doesn't exist
141017 9:24:53 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
141017 9:24:53 InnoDB: The InnoDB memory heap is disabled
141017 9:24:53 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
141017 9:24:53 InnoDB: Compressed tables use zlib 1.2.3
141017 9:24:53 InnoDB: Using Linux native AIO
141017 9:24:53 InnoDB: Initializing buffer pool, size = 128.0M
141017 9:24:53 InnoDB: Completed initialization of buffer pool
InnoDB: The first specified data file ./ibdata1 did not exist:
InnoDB: a new database to be created!
141017 9:24:53 InnoDB: Setting file ./ibdata1 size to 100 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Progress in MB: 100
141017 9:24:58 InnoDB: Log file ./ib_logfile0 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile0 size to 100 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Progress in MB: 100
141017 9:25:03 InnoDB: Log file ./ib_logfile1 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile1 size to 100 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Progress in MB: 100
141017 9:25:08 InnoDB: Log file ./ib_logfile2 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile2 size to 100 MB
InnoDB: Database physically writes the file full: wait...
InnoDB: Progress in MB: 100
InnoDB: Doublewrite buffer not found: creating new
InnoDB: Doublewrite buffer created
InnoDB: 127 rollback segment(s) active.
InnoDB: Creating foreign key constraint system tables
InnoDB: Foreign key constraint system tables created
141017 9:25:13 InnoDB: Waiting for the background threads to start
141017 9:25:14 InnoDB: 5.5.39 started; log sequence number 0
141017 9:25:14 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306
141017 9:25:14 [Note] - '0.0.0.0' resolves to '0.0.0.0';
141017 9:25:14 [Note] Server socket created on IP: '0.0.0.0'.
141017 9:25:14 [ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist
141017 9:26:15 [Warning] Using unique option prefix myisam_recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
141017 9:26:15 [Note] Plugin 'FEDERATED' is disabled.
/usr/libexec/mysqld: Table 'mysql.plugin' doesn't exist
141017 9:26:15 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
141017 9:26:15 InnoDB: The InnoDB memory heap is disabled
141017 9:26:15 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
141017 9:26:15 InnoDB: Compressed tables use zlib 1.2.3
141017 9:26:15 InnoDB: Using Linux native AIO
141017 9:26:15 InnoDB: Initializing buffer pool, size = 128.0M
141017 9:26:15 InnoDB: Completed initialization of buffer pool
141017 9:26:15 InnoDB: highest supported file format is Barracuda.
InnoDB: Log scan progressed past the checkpoint lsn 48941
141017 9:26:15 InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages from the doublewrite
InnoDB: buffer...
InnoDB: Doing recovery: scanned up to log sequence number 1595668
141017 9:26:15 InnoDB: Starting an apply batch of log records to the database...
InnoDB: Progress in percents: 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72
73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
InnoDB: Apply batch completed
141017 9:26:15 InnoDB: Waiting for the background threads to start
141017 9:26:16 InnoDB: 5.5.39 started; log sequence number 1595668
141017 9:26:16 [Note] Recovering after a crash using /data/mysql/mysql_3306/logs/mysql-bin
141017 9:26:16 [Note] Starting crash recovery...
141017 9:26:16 [Note] Crash recovery finished.
141017 9:26:17 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306
141017 9:26:17 [Note] - '0.0.0.0' resolves to '0.0.0.0';
141017 9:26:17 [Note] Server socket created on IP: '0.0.0.0'.
141017 9:26:17 [ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist
141017 9:28:34 [Warning] Using unique option prefix myisam_recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
141017 9:28:34 [Note] Plugin 'FEDERATED' is disabled.
/usr/libexec/mysqld: Can't find file: './mysql/plugin.frm' (errno: 13)
141017 9:28:34 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
141017 9:28:34 InnoDB: The InnoDB memory heap is disabled
141017 9:28:34 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
141017 9:28:34 InnoDB: Compressed tables use zlib 1.2.3
141017 9:28:34 InnoDB: Using Linux native AIO
141017 9:28:34 InnoDB: Initializing buffer pool, size = 128.0M
141017 9:28:34 InnoDB: Completed initialization of buffer pool
141017 9:28:34 InnoDB: highest supported file format is Barracuda.
InnoDB: The log sequence number in ibdata files does not match
InnoDB: the log sequence number in the ib_logfiles!
141017 9:28:34 InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages from the doublewrite
InnoDB: buffer...
141017 9:28:34 InnoDB: Waiting for the background threads to start
141017 9:28:35 InnoDB: 5.5.39 started; log sequence number 1595668
/usr/libexec/mysqld: File '/data/mysql/mysql_3306/logs/mysql-bin.000004' not found (Errcode: 13)
141017 9:28:35 [ERROR] Failed to open log (file '/data/mysql/mysql_3306/logs/mysql-bin.000004', errno 13)
141017 9:28:35 [ERROR] Could not open log file
141017 9:28:35 [ERROR] Can't init tc log
141017 9:28:35 [ERROR] Aborting
141017 9:28:35 InnoDB: Starting shutdown...
141017 9:28:36 InnoDB: Shutdown completed; log sequence number 1595668
141017 9:28:36 [Note] /usr/libexec/mysqld: Shutdown complete
141017 9:30:32 [Warning] Using unique option prefix myisam_recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
141017 9:30:32 [Note] Plugin 'FEDERATED' is disabled.
/usr/libexec/mysqld: Can't find file: './mysql/plugin.frm' (errno: 13)
141017 9:30:32 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
141017 9:30:32 InnoDB: The InnoDB memory heap is disabled
141017 9:30:32 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
141017 9:30:32 InnoDB: Compressed tables use zlib 1.2.3
141017 9:30:32 InnoDB: Using Linux native AIO
141017 9:30:32 InnoDB: Initializing buffer pool, size = 128.0M
141017 9:30:32 InnoDB: Completed initialization of buffer pool
141017 9:30:32 InnoDB: highest supported file format is Barracuda.
141017 9:30:32 InnoDB: Waiting for the background threads to start
141017 9:30:33 InnoDB: 5.5.39 started; log sequence number 1595668
/usr/libexec/mysqld: File '/data/mysql/mysql_3306/logs/mysql-bin.000004' not found (Errcode: 13)
141017 9:30:33 [ERROR] Failed to open log (file '/data/mysql/mysql_3306/logs/mysql-bin.000004', errno 13)
141017 9:30:33 [ERROR] Could not open log file
141017 9:30:33 [ERROR] Can't init tc log
141017 9:30:33 [ERROR] Aborting
141017 9:30:33 InnoDB: Starting shutdown...
141017 9:30:34 InnoDB: Shutdown completed; log sequence number 1595668
141017 9:30:34 [Note] /usr/libexec/mysqld: Shutdown complete
現在error.log裡很明顯地指出errno為13，我們知道13就是權限問題，這個可以perror命令查看
[root@bak mysql]# perror 13
OS error code 13: Permission denied
位置可以通過which來定位
[root@bak mysql]# which perror
/usr/bin/perror
或者用find定位也是可以的
[root@bak mysql]#
find / -name perror -print
/opt/mysql/mysql-5.5.39-linux2.6-i686/bin/perror
/usr/bin/perror
既然找到了無法啟動的真正原因，那麼對症下藥，把權限問題解決，問題就可以搞定了
[root@bak mysql]# cd /data/mysql/mysql_3306/data
[root@bak data]# ll
total 410036
-rw-rw---- 1 mysql mysql 7950 Oct 17 09:30 error.log
-rw-rw---- 1 mysql mysql 104857600 Oct 17 09:30 ibdata1
-rw-rw---- 1 mysql mysql 104857600 Oct 17 09:30 ib_logfile0
-rw-rw---- 1 mysql mysql 104857600 Oct 17 09:25 ib_logfile1
-rw-rw---- 1 mysql mysql 104857600 Oct 17 09:25 ib_logfile2
drwx------ 2 root root 4096 Oct 17 09:28 mysql
drwx------ 2 root root 4096 Oct 17 09:28 performance_schema
drwx------ 2 root root 4096 Oct 17 09:28 test
[root@bak data]# chown -R mysql:mysql ./
[root@bak data]# ll
total 410036
-rw-rw---- 1 mysql mysql 7950 Oct 17 09:30 error.log
-rw-rw---- 1 mysql mysql 104857600 Oct 17 09:30 ibdata1
-rw-rw---- 1 mysql mysql 104857600 Oct 17 09:30 ib_logfile0
-rw-rw---- 1 mysql mysql 104857600 Oct 17 09:25 ib_logfile1
-rw-rw---- 1 mysql mysql 104857600 Oct 17 09:25 ib_logfile2
drwx------ 2 mysql mysql 4096 Oct 17 09:28 mysql
drwx------ 2 mysql mysql 4096 Oct 17 09:28 performance_schema
drwx------ 2 mysql mysql 4096 Oct 17 09:28 test
開始還去調整了/data/mysql/mysql_3306/data目錄下面幾個數據庫的權限，但發現依然無法啟動，看來不是這幾個目錄的權限問題
[root@bak data]# mysqld_safe &
[1] 2988
[root@bak data]# Starting mysqld daemon with databases from /data/mysql/mysql_3306/data
[root@bak data]# mysqlSTOPPING server from pid file /data/mysql/mysql_3306/data/bak.pid
141017 09:32:08 mysqld ended
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
[1]+ Done mysqld_safe
error.log日志內容和之前一樣，仍然報errno 13，就不貼了。針對之前給出的error.log日志裡提示的對mysql-bin.000004讀寫權限的問題做一下處理
[root@bak mysql]# cd /data/mysql/mysql_3306/logs
[root@bak logs]# ll
total 1092
-rw-rw---- 1 mysql mysql 107 Oct 17 09:25 mysql-bin.000001
-rw-rw---- 1 mysql mysql 107 Oct 17 09:26 mysql-bin.000002
-rw-rw---- 1 root root 27681 Oct 17 09:28 mysql-bin.000003
-rw-rw---- 1 root root 1070549 Oct 17 09:28 mysql-bin.000004
-rw-rw---- 1 mysql mysql 180 Oct 17 09:28 mysql-bin.index
[root@bak logs]# chown -R mysql:mysql ./
[root@bak logs]# ll
total 1092
-rw-rw---- 1 mysql mysql 107 Oct 17 09:25 mysql-bin.000001
-rw-rw---- 1 mysql mysql 107 Oct 17 09:26 mysql-bin.000002
-rw-rw---- 1 mysql mysql 27681 Oct 17 09:28 mysql-bin.000003
-rw-rw---- 1 mysql mysql 1070549 Oct 17 09:28 mysql-bin.000004
-rw-rw---- 1 mysql mysql 180 Oct 17 09:28 mysql-bin.index
原來是root root權限，改為mysql mysql了，再次啟動MySQL進程
[root@bak logs]# ps -ef|grep mysql
root 3060 2591 0 09:35 pts/0 00:00:00 grep mysql
[root@bak logs]# mysqld_safe &
[1] 3061
[root@bak logs]# Starting mysqld daemon with databases from /data/mysql/mysql_3306/data
[root@bak logs]# mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.5.39-log MySQL Community Server (GPL)
Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
(testing)root@localhost [(none)]> exit
[root@bak logs]# ps aux | grep -v grep | grep mysql
root 3061 0.0 0.1 4484 1152 pts/0 S 09:35 0:00 /bin/sh /usr/bin/mysqld_safe
mysql 3095 0.0 3.1 330320 32216 pts/0 Sl 09:35 0:02 /usr/libexec/mysqld --basedir=/usr/local/mysql --datadir=/data/mysql/mysql_3306/data --user=mysql
--pid-file=/data/mysql/mysql_3306/data/bak.pid --skip-external-locking --port=3306 --socket=/tmp/mysql.sock
這次，數據庫順利啟動了，從mysql進程中可以看到，mysqld_safe實際去調用的還是mysqld
總結：
當我們遭遇數據庫無法啟動，如：自動終止進程stopping from pid file或是無法通過socket連接到服務器等錯誤，首先要去查看數據庫的error.log日志，其中有詳細的提示（各種ERROR和WARNING），來給你提供無法啟動的線索，我們要做的就是更具這些線索，來做相應的處理，才能更快、更好地解決問題。
