mysql启动后随即关闭问题解决（ibdata1文件损坏致使）

 

机房一台服务器上的mysql运行一段时间了，忽然出现了一个很奇怪的现象：重启后没法恢复了！准确状况是：启动mysql后随即就又关闭了。

查看mysql错误日志以下：

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.

分析日志后发现，数据库没法重启的缘由是由于ibdata1文件损坏，重启后没法正常恢复。

解决办法：
须要跳过恢复步骤，修改my.cnf文件，在my.cnf中的[mysqld]中添加：
innodb_force_recovery = 6
innodb_purge_threads = 1

解释：
innodb_force_recovery能够设置为1-6,大的数字包含前面全部数字的影响。
具体数字对应的含义：
1-----(SRVFORCEIGNORECORRUPT):忽略检查到的corrupt页。
2-----(SRVFORCENOBACKGROUND):阻止主线程的运行，如主线程须要执行full purge操做，会致使crash。
3-----(SRVFORCENOTRXUNDO):不执行事务回滚操做。
4-----(SRVFORCENOIBUFMERGE):不执行插入缓冲的合并操做。
5-----(SRVFORCENOUNDOLOGSCAN):不查看重作日志，InnoDB存储引擎会将未提交的事务视为已提交。
6-----(SRVFORCENOLOG_REDO):不执行前滚的操做。

再次启动mysql就ok了~
若是还没法启动，则须要删除数据目录datafile下的 ibdata1,ib_logfile*等文件。
启动后导出MySQL数据库，从新恢复便可。