228.html

先日サーバーがリソース不足で牛歩状態となり操作不能となったため、強制シャットダウンしました。
そうしたらMySQLが起動しなくなってしまいました。

ログをみると、次のようにでていました。

070901 18:35:43  mysqld started
070901 18:35:43  InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages from the doublewrite
InnoDB: buffer...
070901 18:35:43  InnoDB: Starting log scan based on checkpoint at
InnoDB: log sequence number 1 4073110871.
InnoDB: Doing recovery: scanned up to log sequence number 1 4073111019
InnoDB: 1 transaction(s) which must be rolled back or cleaned up
InnoDB: in total 1 row operations to undo
InnoDB: Trx id counter is 0 140789504
070901 18:35:43  InnoDB: Starting an apply batch of log records to the database...
InnoDB: Progress in percents: 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: Starting rollback of uncommitted transactions
InnoDB: Rolling back trx with id 0 140789009, 1 rows to undoInnoDB: Error: trying to access page number 532303 in space 0,
InnoDB: space name ./ibdata1,
InnoDB: which is outside the tablespace bounds.
InnoDB: Byte offset 0, len 16384, i/o type 10
070901 18:35:43InnoDB: Assertion failure in thread 1128208 in file fil0fil.c line 3922
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/mysql/en/Forcing_recovery.html
InnoDB: about forcing recovery.
mysqld got signal 11;
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.

key_buffer_size=0
read_buffer_size=131072
max_used_connections=0
max_connections=100
threads_connected=0
It is possible that mysqld could use up to 
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_connections = 217599 K
bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

thd=(nil)
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
Cannot determine thread, fp=0xbfee8088, backtrace may not be correct.
Stack range sanity check OK, backtrace follows:
0x812b880
0xa44420
0x82931de
0x82931de
0x8285901
0x82b2f4d
0x82b2331
0x826a9c8
0x8281f9e
0x827a4f4
0x8274b09
0x821206e
0x8212798
0x8272f85
0x82a1126
0x81f97e2
0x81b119f
0x81a8925
0x812ccde
0x812d279
0xbcc724
0x80c7031
New value of fp=(nil) failed sanity check, terminating stack trace!
Please read http://dev.mysql.com/doc/mysql/en/Using_stack_trace.html and follow instructions on how to resolve the stack trace. Resolved
stack trace is much more helpful in diagnosing the problem, so please do 
resolve it
The manual page at http://www.mysql.com/doc/en/Crashing.html contains
information that should help you find out what is causing the crash.
070901 18:35:43  mysqld ended

どうやら、未コミットなトランザクションなどのリカバリに失敗している、とかそういう感じでしょうか。
エラーログにある、
MySQL AB :: MySQL 4.1 リファレンスマニュアル :: 7.5.7.1 強制的なリカバリ
http://dev.mysql.com/doc/refman/4.1/ja/forcing-recovery.html
の内容などを参考にして、my.cnfに、
```
[mysqld]
innodb_force_recovery=3
```
などを追加して起動はすることができました。
でも、selectはできますが、drop tableなどは
```
InnoDB: !!! innodb_force_recovery is set to 3 !!!
```
といったエラーがエラーログにでて、実行できません。
マニュアルには、drop tableはできる、と書いてあるのに。
同様に、SELECT INTO OUTFILEはできますが、LOAD DATA INFILEも同じエラーがでて実行できませんでした。
なので、次のような手順で対応しました。
1. 今の、datadir /var/lib/mysqlを一応 /var/lib/mysql_backにバックアップ
2. /etc/my.cnfに次を追記して、InnoDBを強制リカバリモードで起動
```
     [mysqld]
     innodb_force_recovery = 3
```
3. 全データベースをダンプ
```
     mysqldump --default-character-set=latin1 databasename > databasename.sql
       ....
```
4. mysqldがシャットダウンできないので、強制 kill
```
     ps xa | grep mysql
     kill -9 safe_mysqldのpid
     kill -9 mysqldのpid
```
5. /var/lib/msyql2 というディレクトリを作成
6. mysql_install_dbを--datadirを指定して /var/lib/mysql2 を初期化
```
     mysql_install_db --datadir /var/lib/mysql2
```
7. /etc/init.d/mysqlのdatadirの記述の部分を、/var/lib/mysql2に変更
```
     # Set some defaults
     datadir=/var/lib/mysql2
```
8. /etc/my.cnfの、「innodb_force_recovery = 3」を消してmysqlを起動
```
     /etc/init.d/mysql start
```
9. 新しいmysqlに、DBを作って、ダンプしたデータをロード
```
     mysqladmin create databasename; mysql databasename < databasename.sql
```