mysql啓動後隨即關閉問題解決（ibdata1文件損壞致使）

 

機房一臺服務器上的mysql運行一段時間了，忽然出現了一個很奇怪的現象：重啓後沒法恢復了！準確狀況是：啓動mysql後隨即就又關閉了。

查看mysql錯誤日誌以下：

160920 22:41:41 mysqld_safe Starting mysqld daemon with databases from /home/MysqlData/
2016-09-20 22:41:41 0 [Note] /Data/app/mysql5.6.25/bin/mysqld (mysqld 5.6.25-log) starting as process 32372 ...
2016-09-20 22:41:42 32372 [Note] Plugin 'FEDERATED' is disabled.
2016-09-20 22:41:42 32372 [Warning] option 'innodb-write-io-threads': unsigned value 1000 adjusted to 64
2016-09-20 22:41:42 32372 [Warning] option 'innodb-read-io-threads': unsigned value 1000 adjusted to 64
2016-09-20 22:41:42 32372 [Note] InnoDB: Using atomics to ref count buffer pool pages
2016-09-20 22:41:42 32372 [Note] InnoDB: The InnoDB memory heap is disabled
2016-09-20 22:41:42 32372 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2016-09-20 22:41:42 32372 [Note] InnoDB: Memory barrier is not used
2016-09-20 22:41:42 32372 [Note] InnoDB: Compressed tables use zlib 1.2.3
2016-09-20 22:41:42 32372 [Note] InnoDB: Using CPU crc32 instructions
2016-09-20 22:41:42 32372 [Note] InnoDB: Initializing buffer pool, size = 1.0G
2016-09-20 22:41:42 32372 [Note] InnoDB: Completed initialization of buffer pool
2016-09-20 22:41:42 32372 [Note] InnoDB: Highest supported file format is Barracuda.
2016-09-20 22:41:42 32372 [Note] InnoDB: Log scan progressed past the checkpoint lsn 20293587957
2016-09-20 22:41:42 32372 [Note] InnoDB: Database was not shutdown normally!
2016-09-20 22:41:42 32372 [Note] InnoDB: Starting crash recovery.
2016-09-20 22:41:42 32372 [Note] InnoDB: Reading tablespace information from the .ibd files...
2016-09-20 22:41:42 32372 [Note] InnoDB: Restoring possible half-written data pages
2016-09-20 22:41:42 32372 [Note] InnoDB: from the doublewrite buffer...
InnoDB: Doing recovery: scanned up to log sequence number 20293596130
2016-09-20 22:41:42 32372 [Note] InnoDB: Starting an apply batch of log records to the database...
InnoDB: Progress in percent: 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
InnoDB: Apply batch completed
InnoDB: Last MySQL binlog file position 0 136254, file name mysql-bin.000013
2016-09-20 22:41:43 32372 [Note] InnoDB: 128 rollback segment(s) are active.
2016-09-20 22:41:43 32372 [Note] InnoDB: Waiting for purge to start
2016-09-20 22:41:43 7f77a9edd700 InnoDB: Assertion failure in thread 140151928772352 in file trx0purge.cc line 699
InnoDB: Failing assertion: purge_sys->iter.trx_no <= purge_sys->rseg->last_trx_no
InnoDB: We intentionally generate a memory trap.
InnoDB: Submit a detailed bug report to http://bugs.mysql.com.
InnoDB: If you get repeated assertion failures or crashes, even
InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: http://dev.mysql.com/doc/refman/5.6/en/forcing-innodb-recovery.html
InnoDB: about forcing recovery.
02:41:43 UTC - mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
We will try our best to scrape up some info that will hopefully help
diagnose the problem, but since we have already crashed,
something is definitely wrong and this may fail.

分析日誌後發現，數據庫沒法重啓的緣由是由於ibdata1文件損壞，重啓後沒法正常恢復。

解決辦法：
須要跳過恢復步驟，修改my.cnf文件，在my.cnf中的[mysqld]中添加：
innodb_force_recovery = 6
innodb_purge_threads = 1

解釋：
innodb_force_recovery能夠設置爲1-6,大的數字包含前面全部數字的影響。
具體數字對應的含義：
1-----(SRVFORCEIGNORECORRUPT):忽略檢查到的corrupt頁。
2-----(SRVFORCENOBACKGROUND):阻止主線程的運行，如主線程須要執行full purge操做，會致使crash。
3-----(SRVFORCENOTRXUNDO):不執行事務回滾操做。
4-----(SRVFORCENOIBUFMERGE):不執行插入緩衝的合併操做。
5-----(SRVFORCENOUNDOLOGSCAN):不查看重作日誌，InnoDB存儲引擎會將未提交的事務視爲已提交。
6-----(SRVFORCENOLOG_REDO):不執行前滾的操做。

再次啓動mysql就ok了~
若是還沒法啓動，則須要刪除數據目錄datafile下的 ibdata1,ib_logfile*等文件。
啓動後導出MySQL數據庫，從新恢復便可。