建立數據庫連接時出錯-WordPress和MySQL

Question

我的WordPress網站經常出現Error establishing a database connection 。

以前，我使用sudo chmod 755 /var/lib/mysql和sudo /etc/init.d/mysql restart進行修復。 但是，這一次，他們再也無法工作了。 sudo /etc/init.d/mysql返回

stop: Unknown instance: 
start: Job failed to start

和mysqld --verbose返回

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

有誰知道如何使我的網站恢復正常？

Answer 1

您的Droplet沒有足夠的內存來啟動MySQL。 看到錯誤InnoDB: mmap(137363456 bytes) failed; errno 12 InnoDB: mmap(137363456 bytes) failed; errno 12嘗試分配〜130MB內存時MySQL失敗。
運行free -m以檢查應用程序有多少可用內存。

您可以通過兩種方式解決此問題：

1. 增加液滴的大小。 這將花費您更多的錢。
2. 向您的Droplet添加（更多）交換空間。 這很可能會影響性能，但可以節省您的錢。