My WordPress website often has the error Error establishing a database connection.
Previously, I used sudo chmod 755 /var/lib/mysql and sudo /etc/init.d/mysql restart to fix it. However, this time, they could not work anymore; sudo /etc/init.d/mysql returned
stop: Unknown instance:
start: Job failed to start
And mysqld --verbose returned
180120 3:24:48 [Warning] Using unique option prefix key_buffer instead of key_buffer_size is deprecated and will be removed in a future release. Please use the full name instead.
180120 3:24:48 [Warning] Can't create test file /var/lib/mysql/chengtie.lower-test
180120 3:24:48 [Note] mysqld (mysqld 5.5.58-0ubuntu0.14.04.1) starting as process 20724 ...
180120 3:24:48 [Warning] Can't create test file /var/lib/mysql/chengtie.lower-test
180120 3:24:48 [Warning] Can't create test file /var/lib/mysql/chengtie.lower-test
180120 3:24:48 [Warning] One can only use the --user switch if running as root
180120 3:24:48 [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.
180120 3:24:48 [Note] Plugin 'FEDERATED' is disabled.
mysqld: Can't find file: './mysql/plugin.frm' (errno: 13)
180120 3:24:48 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
180120 3:24:48 InnoDB: The InnoDB memory heap is disabled
180120 3:24:48 InnoDB: Mutexes and rw_locks use GCC atomic builtins
180120 3:24:48 InnoDB: Compressed tables use zlib 1.2.8
180120 3:24:48 InnoDB: Using Linux native AIO
180120 3:24:48 InnoDB: Initializing buffer pool, size = 128.0M
InnoDB: mmap(137363456 bytes) failed; errno 12
180120 3:24:48 InnoDB: Completed initialization of buffer pool
180120 3:24:48 InnoDB: Fatal error: cannot allocate memory for the buffer pool
180120 3:24:48 [ERROR] Plugin 'InnoDB' init function returned error.
180120 3:24:48 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
180120 3:24:48 [ERROR] Unknown/unsupported storage engine: InnoDB
180120 3:24:48 [ERROR] Aborting
180120 3:24:48 [Note] mysqld: Shutdown complete
Does anyone know how to make my website back?
InnoDB: mmap(137363456 bytes) failed; errno 12- looks like your instance is out of memory? how much memory does the droplet have and how much is available when you try starting mysql?512MB, there are other small websites running on it as well. How can I see how much memory is available when I try starting mysql?