Link to database cannot be established

Jun 16, 2016
5
0
1
Karachi
cPanel Access Level
Root Administrator
Its not often but am getting error (usually 2 or more time a day) when i am trying to open my site "Link to database cannot be established: SQLSTATE[HY000] [2006] MySQL server has gone away" at this stage my site not respond anything. If i restart mysql service ever thing back to normal but not for long.

What should i need to do to resolve that issue???

Configuration---
CENTOS 6.7 x86_64 vmware
WHM 54.0 (build 16)
MYSQL Server version: 5.5.48-cll
 

ssfred

Well-Known Member
Jan 6, 2012
65
4
58
India
cPanel Access Level
Root Administrator
Twitter
Hello :)

Please check the current MySQL activity during the time of the issue by executing the following command

From Shell:

#mysqladmin proc stat

From MySQL Shell

mysql> show processlist;

Also check the MySQL server logs /var/lib/mysql/hostname.err for any error messages.
 
Jun 16, 2016
5
0
1
Karachi
cPanel Access Level
Root Administrator
hello ssfred
Thanks for the reply. the only thing what i checked is MySQL server logs but i will check you suggested command during the issue. please check MySQL server logs.

- Removed Please Attach Images to Your Posts -
 
Last edited by a moderator:
Jun 16, 2016
5
0
1
Karachi
cPanel Access Level
Root Administrator
Hi twhiting,
Thanks for the response. My current logs say at the time as follow...

Code:
150729 01:37:24 mysqld_safe Starting mysqld daemon with databases from /var/lib/  mysql
150729  1:37:24 [Note] Plugin 'FEDERATED' is disabled.
150729  1:37:24 InnoDB: The InnoDB memory heap is disabled
150729  1:37:24 InnoDB: Mutexes and rw_locks use GCC atomic builtins
150729  1:37:24 InnoDB: Compressed tables use zlib 1.2.3
150729  1:37:24 InnoDB: Using Linux native AIO
150729  1:37:24 InnoDB: Initializing buffer pool, size = 128.0M
150729  1:37:24 InnoDB: Completed initialization of buffer pool
InnoDB: The first specified data file ./ibdata1 did not exist:
InnoDB: a new database to be created!
150729  1:37:24  InnoDB: Setting file ./ibdata1 size to 10 MB
InnoDB: Database physically writes the file full: wait...
150729  1:37:24  InnoDB: Log file ./ib_logfile0 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile0 size to 5 MB
InnoDB: Database physically writes the file full: wait...
150729  1:37:24  InnoDB: Log file ./ib_logfile1 did not exist: new to be created
InnoDB: Setting log file ./ib_logfile1 size to 5 MB
InnoDB: Database physically writes the file full: wait...
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
150729  1:37:25  InnoDB: Waiting for the background threads to start
150729  1:37:26 InnoDB: 5.5.42 started; log sequence number 0
150729  1:37:26 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306
150729  1:37:26 [Note]  - '0.0.0.0' resolves to '0.0.0.0';
150729  1:37:26 [Note] Server socket created on IP: '0.0.0.0'.
150729  1:37:26 [Note] Event Scheduler: Loaded 0 events
150729  1:37:26 [Note] /usr/sbin/mysqld: ready for connections.
Version: '5.5.42-cll'  socket: '/var/lib/mysql/mysql.sock'  port: 3306  MySQL Co  mmunity Server (GPL)
150729  1:37:32 [Note] /usr/sbin/mysqld: Normal shutdown

150729  1:37:32 [Note] Event Scheduler: Purging the queue. 0 events
150729  1:37:34  InnoDB: Starting shutdown...
150729  1:37:35  InnoDB: Shutdown completed; log sequence number 1595675
150729  1:37:35 [Note] /usr/sbin/mysqld: Shutdown complete

150729 01:37:35 mysqld_safe mysqld from pid file /var/lib/mysql/srv.server.com.p  id ended
150729 01:37:35 mysqld_safe Starting mysqld daemon with databases from /var/lib/  mysql
150729  1:37:35 [Note] Plugin 'FEDERATED' is disabled.
150729  1:37:35 InnoDB: The InnoDB memory heap is disabled
150729  1:37:35 InnoDB: Mutexes and rw_locks use GCC atomic builtins
150729  1:37:35 InnoDB: Compressed tables use zlib 1.2.3
150729  1:37:35 InnoDB: Using Linux native AIO
150729  1:37:35 InnoDB: Initializing buffer pool, size = 128.0M
150729  1:37:35 InnoDB: Completed initialization of buffer pool
150729  1:37:35 InnoDB: highest supported file format is Barracuda.
150729  1:37:35  InnoDB: Waiting for the background threads to start
150729  1:37:36 InnoDB: 5.5.42 started; log sequence number 1595675
150729  1:37:36 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306
150729  1:37:36 [Note]  - '0.0.0.0' resolves to '0.0.0.0';
150729  1:37:36 [Note] Server socket created on IP: '0.0.0.0'.
150729  1:37:36 [Note] Event Scheduler: Loaded 0 events
150729  1:37:36 [Note] /usr/sbin/mysqld: ready for connections.
Version: '5.5.42-cll'  socket: '/var/lib/mysql/mysql.sock'  port: 3306  MySQL Co  mmunity Server (GPL)
150729  2:42:29 [Note] /usr/sbin/mysqld: Normal shutdown

150729  2:42:29 [Note] Event Scheduler: Purging the queue. 0 events
150729  2:42:31 [Warning] /usr/sbin/mysqld: Forcing close of thread 71  user: 'e  ximstats'

150729  2:42:31 [Warning] /usr/sbin/mysqld: Forcing close of thread 64  user: 'l  eechprotect'

150729  2:42:31  InnoDB: Starting shutdown...
150729  2:42:33  InnoDB: Shutdown completed; log sequence number 1683063
150729  2:42:33 [Note] /usr/sbin/mysqld: Shutdown complete

150729 02:42:33 mysqld_safe mysqld from pid file /var/lib/mysql/srv.server.com.p  id ended
and currently my site is down.
- Removed -
please help..
 
Last edited by a moderator:

ssfred

Well-Known Member
Jan 6, 2012
65
4
58
India
cPanel Access Level
Root Administrator
Twitter
Hello :)

Check whether there is any memory availability issues. Some times OOM killer may trigger termination of MySQL processes, if the primary memory availability is low and MySQL is showing a high memory usage. You check it using the command

#egrep -i "oom|kill|mysql" /var/log/messages