問題介紹
電腦在使用過程中當機，重新啟動後發現mysql沒有啟動成功，查看錯誤日誌發現是innodb出現問題導致mysql啟動失敗。
錯誤日誌
$ mysql.server start Starting MySQL . ERROR! The server quit without updating PID file (/usr/local/var/mysql/fdipzonedeMacBook-Air.local.pid). 22:08:37 mysqld_safe Starting mysqld daemon with databases from /usr/local/var/mysql 2016-04-23 22:08:38 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details). 2016-04-23 22:08:38 0 [Note] /usr/local/Cellar/mysql/5.6.24/bin/mysqld (mysqld 5.6.24) starting as process 3604 ... 2016-04-23 22:08:38 3604 [Warning] Setting lower_case_table_names=2 because file system for /usr/local/var/mysql/ is case insensitive 2016-04-23 22:08:38 3604 [Note] Plugin 'FEDERATED' is disabled. 2016-04-23 22:08:38 3604 [Note] InnoDB: Using atomics to ref count buffer pool pages 2016-04-23 22:08:38 3604 [Note] InnoDB: The InnoDB memory heap is disabled 2016-04-23 22:08:38 3604 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins 2016-04-23 22:08:38 3604 [Note] InnoDB: Memory barrier is not used 2016-04-23 22:08:38 3604 [Note] InnoDB: Compressed tables use zlib 1.2.3 2016-04-23 22:08:38 3604 [Note] InnoDB: Using CPU crc32 instructions 2016-04-23 22:08:38 3604 [Note] InnoDB: Initializing buffer pool, size = 128.0M 2016-04-23 22:08:38 3604 [Note] InnoDB: Completed initialization of buffer pool 2016-04-23 22:08:38 3604 [Note] InnoDB: Highest supported file format is Barracuda. 2016-04-23 22:08:38 3604 [Note] InnoDB: Log scan progressed past the checkpoint lsn 68929933440 2016-04-23 22:08:38 3604 [Note] InnoDB: Database was not shutdown normally! 2016-04-23 22:08:38 3604 [Note] InnoDB: Starting crash recovery. 2016-04-23 22:08:38 3604 [Note] InnoDB: Reading tablespace information from the .ibd files... 2016-04-23 22:08:38 3604 [ERROR] InnoDB: checksum mismatch in tablespace ./test_user/user_recommend_code#P#pmax.ibd (table test_user/user_recommend_code#P#pmax) 2016-04-23 22:08:38 3604 [Note] InnoDB: Page size:1024 Pages to analyze:64 2016-04-23 22:08:38 3604 [Note] InnoDB: Page size: 1024, Possible space_id count:0 2016-04-23 22:08:38 3604 [Note] InnoDB: Page size:2048 Pages to analyze:48 2016-04-23 22:08:38 3604 [Note] InnoDB: Page size: 2048, Possible space_id count:0 2016-04-23 22:08:38 3604 [Note] InnoDB: Page size:4096 Pages to analyze:24 2016-04-23 22:08:38 3604 [Note] InnoDB: Page size: 4096, Possible space_id count:0 2016-04-23 22:08:38 3604 [Note] InnoDB: Page size:8192 Pages to analyze:12 2016-04-23 22:08:38 3604 [Note] InnoDB: Page size: 8192, Possible space_id count:0 2016-04-23 22:08:38 3604 [Note] InnoDB: Page size:16384 Pages to analyze:6 2016-04-23 22:08:38 3604 [Note] InnoDB: VALID: space:2947354 page_no:3 page_size:16384 2016-04-23 22:08:38 3604 [Note] InnoDB: Page size: 16384, Possible space_id count:1 2016-04-23 22:08:38 3604 [Note] InnoDB: space_id:2947354, Number of pages matched: 1/1 (16384) 2016-04-23 22:08:38 3604 [Note] InnoDB: Chosen space:2947354 2016-04-23 22:08:38 3604 [Note] InnoDB: Restoring page 0 of tablespace 2947354 2016-04-23 22:08:38 3604 [Warning] InnoDB: Doublewrite does not have page_no=0 of space: 2947354 2016-04-23 22:08:38 7fff79b9e300 InnoDB: Operating system error number 2 in a file operation. InnoDB: The error means the system cannot find the path specified. InnoDB: If you are installing InnoDB, remember that you must create InnoDB: directories yourself, InnoDB does not create them. InnoDB: Error: could not open single-table tablespace file ./test_user/user_recommend_code#P#pmax.ibd InnoDB: We do not continue the crash recovery, because the table may become InnoDB: corrupt if we cannot apply the log records in the InnoDB log to it. InnoDB: To fix the problem and start mysqld: InnoDB: 1) If there is a permission problem in the file and mysqld cannot InnoDB: open the file, you should modify the permissions. InnoDB: 2) If the table is not needed, or you can restore it from a backup, InnoDB: then you can remove the .ibd file, and InnoDB will do a normal InnoDB: crash recovery and ignore that table. InnoDB: 3) If the file system or the disk is broken, and you cannot remove InnoDB: the .ibd file, you can set innodb_force_recovery > 0 in my.cnf InnoDB: and force InnoDB to continue crash recovery here.
解決方法
1.如果資料不重要或已經有備份，只需要恢復mysql啟動
進入mysql目錄，一般是： /usr/local/var/mysql/
刪除ib_logfile*
刪除ibdata*
刪除所有資料庫實體目錄（例如資料庫為test_db,則執行rm -rf test_db）
重啟動mysql
重新建立資料庫或使用備份覆蓋
2.如果資料很重要且沒有備份
可以使用innodb_force_recovery參數，使mysqld跳過復原步驟，啟動mysqld，將資料匯出然後重建資料庫。
innodb_force_recovery 可以設定為1-6，大的數字包含前面所有數字的影響
1、(SRV_FORCE_IGNORE_CORRUPT):忽略檢查到的corrupt頁。
2、(SRV_FORCE_NO_BACKGROUND):阻止主執行緒的運行，如主執行緒需要執行full purge操作，會導致crash。
3、(SRV_FORCE_NO_TRX_UNDO):不執行交易回溯作業。
4、(SRV_FORCE_NO_IBUF_MERGE):不執行插入緩衝的合併作業。
5、(SRV_FORCE_NO_UNDO_LOG_SCAN):不查看重做日誌，InnoDB儲存引擎會將未提交的交易視為已提交。
6、(SRV_FORCE_NO_LOG_REDO):不執行前滾的操作。
在my.cnf(windows是my.ini)加入
innodb_force_recovery = 6 innodb_purge_thread = 0
重啟mysql
這時只可以執行select,create,drop操作，但不能執行insert,update,delete操作
執行邏輯匯出，完成後將innodb_force_recovery=0，innodb_purge_threads=1，然後重建資料庫，最後把匯出的資料重新匯入
總結
以上就是這篇文章的全部內容，希望能對大家學習或使用mysql的時候有所幫助，如果有疑問大家可以留言交流，謝謝大家對的支持。
