前言

innodb_data_file_path用來指定innodb tablespace檔案，如果我們不在My.cnf檔案中指定innodb_data_home_dir和innodb_data_file_path那麼預設會在datadir目錄下建立ibdata1 作為innodb tablespace。

說明

在測試環境下沒有設定過多的詳細引數就初始化並啟動了服務，後期優化的過程中發現innodb_data_file_path設定過小：

root@node1 14:59: [(none)]> show variables like '%innodb_data_file_path%';
+-----------------------+------------------------+
| Variable_name | Value  |
+-----------------------+------------------------+
| innodb_data_file_path | ibdata1:12M:autoextend |
+-----------------------+------------------------+
1 row in set (0.00 sec)

root@node1 14:59: [(none)]>

當沒有配置innodb_data_file_path時，預設innodb_data_file_path = ibdata1:12M:autoextend

[mysqld]
innodb_data_file_path = ibdata1:12M:autoextend

當需要改為1G時，不能直接在配置檔案把 ibdata1 改為 1G,

[mysqld]
innodb_data_file_path = ibdata1:1G:autoextend

否則啟動服務之後，從錯誤日誌看到如下報錯：

2019-03-29T06:47:32.044316Z 0 [ERROR] InnoDB: The Auto-extending innodb_system data file './ibdata1' is of a different size 768 pages (rounded down to MB) than specified in the .cnf file: initial 65536 pages,max 0 (relevant if non-zero) pages!

大致意思就是ibdata1的大小不是 65536page*16KB/1024KB=1G ,而是 786page*16KB/1024KB=12M
（未使用壓縮頁）

方法一：推薦

而應該再新增一個 ibdata2:1G ，如下：

[mysqld]
innodb_data_file_path = ibdata1:12M;ibdata2:1G:autoextend

重啟資料庫！

方法二：不推薦

直接改為如下的話

[mysqld]
innodb_data_file_path = ibdata1:1G:autoextend

可以刪除$mysql_datadir目錄下 ibdata1、ib_logfile0、ib_logfile1 檔案：

rm -f ibdata* ib_logfile*

也可以啟動MySQL，但是mysql錯誤日誌裡會報如下錯誤：

2019-03-29T07:10:47.844560Z 0 [Warning] Could not increase number of max_open_files to more than 5000 (request: 65535)
2019-03-29T07:10:47.844686Z 0 [Warning] Changed limits: table_open_cache: 1983 (requested 2000)
2019-03-29T07:10:48.028262Z 0 [Warning] 'NO_AUTO_CREATE_USER' sql mode was not set.
2019-03-29T07:10:48.147653Z 0 [Warning] InnoDB: Cannot open table mysql/plugin from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
mysqld: Table 'mysql.plugin' doesn't exist
2019-03-29T07:10:48.147775Z 0 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
2019-03-29T07:10:48.163444Z 0 [Warning] InnoDB: Cannot open table mysql/gtid_executed from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
mysqld: Table 'mysql.gtid_executed' doesn't exist
2019-03-29T07:10:48.163502Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2019-03-29T07:10:48.163658Z 0 [Warning] InnoDB: Cannot open table mysql/gtid_executed from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
mysqld: Table 'mysql.gtid_executed' doesn't exist
2019-03-29T07:10:48.163711Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2019-03-29T07:10:48.164619Z 0 [Warning] Failed to set up SSL because of the following SSL library error: SSL context is not usable without certificate and private key
2019-03-29T07:10:48.166805Z 0 [Warning] InnoDB: Cannot open table mysql/server_cost from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
2019-03-29T07:10:48.166891Z 0 [Warning] Failed to open optimizer cost constant tables

2019-03-29T07:10:48.168072Z 0 [Warning] InnoDB: Cannot open table mysql/time_zone_leap_second from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
2019-03-29T07:10:48.168165Z 0 [Warning] Can't open and lock time zone table: Table 'mysql.time_zone_leap_second' doesn't exist trying to live without them
2019-03-29T07:10:48.169454Z 0 [Warning] InnoDB: Cannot open table mysql/servers from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
2019-03-29T07:10:48.169527Z 0 [ERROR] Can't open and lock privilege tables: Table 'mysql.servers' doesn't exist
2019-03-29T07:10:48.170042Z 0 [Warning] InnoDB: Cannot open table mysql/slave_master_info from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
2019-03-29T07:10:48.170617Z 0 [Warning] InnoDB: Cannot open table mysql/slave_relay_log_info from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
2019-03-29T07:10:48.170946Z 0 [Warning] InnoDB: Cannot open table mysql/slave_master_info from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
2019-03-29T07:10:48.171046Z 0 [Warning] Info table is not ready to be used. Table 'mysql.slave_master_info' cannot be opened.
2019-03-29T07:10:48.171272Z 0 [Warning] InnoDB: Cannot open table mysql/slave_worker_info from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
2019-03-29T07:10:48.171626Z 0 [Warning] InnoDB: Cannot open table mysql/slave_relay_log_info from the internal data dictionary of InnoDB though the .frm file for the table exists. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting.html for how to resolve the issue.
2019-03-29T07:10:48.171688Z 0 [Warning] Info table is not ready to be used. Table 'mysql.slave_relay_log_info' cannot be opened.

總結

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