崩溃恢复（crash recovery）与 AUTORESTART参数

这个参数解释如下：
       如果DB2数据库遭受断电或者异常关闭，数据库没有干净的关闭，那么数据库在启动的时候将会进行crash recovery. 但是如果数据库参数AUTORESTART设置为OFF的话，在启动数据库后DB2不会进行CRASH RECOVERY。关于crash recovery，在db2diag.log日志会有相关体现

下面重现这一场景：

/* 1   设置AUTORESTART为OFF   */ [db2inst1@limt ~]$ db2 UPDATE DATABASE CONFIGURATION for limtdb USING AUTORESTART OFF IMMEDIATE DB20000I  The UPDATE DATABASE CONFIGURATION command completed successfully. [db2inst1@limt ~]$ db2 get db cfg for limtdb|grep -i AUTORESTART  Auto restart enabled                      (AUTORESTART) = OFF   [db2inst1@limt yunwei]$ db2 connect to limtdb     Database Connection Information   Database server        = DB2/LINUXX8664 10.1.0  SQL authorization ID   = DB2INST1  Local database alias   = LIMTDB  /* 2   插入一条数据但不提交，为了数据库处于不一致性   */ [db2inst1@limt yunwei]$ db2  +c "insert into A values(15485,'asdas','asdas')" DB20000I  The SQL command completed successfully. [db2inst1@limt yunwei]$  /* 3  kill数据库，模拟异常宕机情况   */ [db2inst1@limt yunwei]$ ps -ef|grep db2sys db2inst1  5287  5285  1 08:07 pts/1    00:00:04 db2sysc 0                                       db2inst1  5827  3612  0 08:12 pts/1    00:00:00 grep db2sys [db2inst1@limt yunwei]$ kill -9 5287 /* 4  启动数据库，此时数据库没有进行崩溃恢复，因为AUTORESTART为OFF  */ [db2inst1@limt yunwei]$  [db2inst1@limt yunwei]$ db2start 12/19/2014 08:13:04     0   0   SQL1063N  DB2START processing was successful. SQL1063N  DB2START processing was successful. [db2inst1@limt yunwei]$  [db2inst1@limt yunwei]$  /* 5  此处报错是因为刚才的db2bp进程没有terminate  */ [db2inst1@limt yunwei]$ db2 connect to limtdb SQL0752N  Connecting to a database is not permitted within a logical unit of  work when the CONNECT type 1 setting is in use.  SQLSTATE=0A001 [db2inst1@limt yunwei]$ db2 terminate DB20000I  The TERMINATE command completed successfully. /* 6  再次启动时候报数据库不一致 */ [db2inst1@limt yunwei]$ db2 connect to limtdb SQL1015N  The database is in an inconsistent state.  SQLSTATE=55025 /* 7  db2 ? SQL1015N 有一条建议： using the RESTART DATABASE command*/ [db2inst1@limt yunwei]$ db2 restart database limtdb DB20000I  The RESTART DATABASE command completed successfully.  /* 8  数据库可以正常连接*/ [db2inst1@limt yunwei]$ db2 connect to limtdb     Database Connection Information   Database server        = DB2/LINUXX8664 10.1.0  SQL authorization ID   = DB2INST1  Local database alias   = LIMTDB  /* 9   以下是设置AUTORESTART为ON情况下，数据库宕机重启(不需要执行RESTART DATABASE) */ [db2inst1@limt yunwei]$  [db2inst1@limt yunwei]$ db2 UPDATE DATABASE CONFIGURATION for limtdb USING AUTORESTART ON IMMEDIATE DB20000I  The UPDATE DATABASE CONFIGURATION command completed successfully. [db2inst1@limt yunwei]$  [db2inst1@limt yunwei]$ db2 get db cfg for limtdb|grep -i AUTORESTART  Auto restart enabled                      (AUTORESTART) = ON [db2inst1@limt yunwei]$  [db2inst1@limt yunwei]$  [db2inst1@limt yunwei]$ db2  +c "insert into A values(15485,'asdas','asdas')" DB20000I  The SQL command completed successfully. [db2inst1@limt yunwei]$ ps -ef|grep db2sys db2inst1  5870  5868  1 08:13 pts/1    00:00:03 db2sysc 0                                       db2inst1  6122  3612  0 08:16 pts/1    00:00:00 grep db2sys [db2inst1@limt yunwei]$ kill -9 5870 [db2inst1@limt yunwei]$ db2start 12/19/2014 08:16:35     0   0   SQL1063N  DB2START processing was successful. SQL1063N  DB2START processing was successful. [db2inst1@limt yunwei]$ db2 connect to limtdb SQL0752N  Connecting to a database is not permitted within a logical unit of  work when the CONNECT type 1 setting is in use. [db2inst1@limt yunwei]$ db2 terminate DB20000I  The TERMINATE command completed successfully. [db2inst1@limt yunwei]$ db2 connect to limtdb     Database Connection Information   Database server        = DB2/LINUXX8664 10.1.0  SQL authorization ID   = DB2INST1  Local database alias   = LIMTDB