1、 查看默认情况下的设置：
db2 get db cfg for db_name |grep -i log
结果如下：
Log retain for recovery enabled (LOGRETAIN) = OFF
User exit for logging enabled (USEREXIT) = OFF
HADR log write synchronization mode (HADR_SYNCMODE) = NEARSYNC
First log archive method (LOGARCHMETH1) = OFF
默认情况为循环日志
2、更改为归档日志：
db2 update db cfg for db_name using LOGRETAIN ON
运行后结果如下：
Log retain for recovery enabled (LOGRETAIN) = RECOVERY
User exit for logging enabled (USEREXIT) = OFF
HADR log write synchronization mode (HADR_SYNCMODE) = NEARSYNC
First log archive method (LOGARCHMETH1) = LOGRETAIN、
更改归档目录:
db2 update db cfg for db_name using LOGARCHMETH1 "disk:/archive/db_name_db_log"
运行后结果如下：
Log retain for recovery enabled (LOGRETAIN) = RECOVERY
User exit for logging enabled (USEREXIT) = OFF
HADR log write synchronization mode (HADR_SYNCMODE) = NEARSYNC
First log archive method (LOGARCHMETH1) =
DISK:/archivelog/db_name_db_log/
3、手工归档方法：
db2 archive log for db db_name
（但前提是没数据库连接，很奇怪，不知道为什么）
如下：
[db2inst1@home SQLOGDIR]$ db2 connect to fangys
Database Connection Information
Database server = DB2/LINUX 8.2.9
SQL authorization ID = DB2INST1
Local database alias = FANGYS
[db2inst1@home SQLOGDIR]$ db2 archive log for db fangys
SQL1493N The application is already connected to an active database.
-------不知道为什么不行！！！！
[db2inst1@home SQLOGDIR]$ db2 connect reset
DB20000I The SQL command completed successfully.
[db2inst1@home SQLOGDIR]$ db2_ps
Node 0
UID PID PPID C STIME TTY TIME CMD
db2inst1 6608 6607 0 21:30 pts/1 00:00:00 db2sysc 0
root 6609 6608 0 21:30 pts/1 00:00:00 db2ckpwd 0
root 6610 6608 0 21:30 pts/1 00:00:00 db2ckpwd 0
root 6611 6608 0 21:30 pts/1 00:00:00 db2ckpwd 0
root 6612 6608 0 21:30 pts/1 00:00:00 db2pmd 0
db2inst1 6613 6608 0 21:30 pts/1 00:00:00 db2gds 0
db2inst1 6615 6608 0 21:30 pts/1 00:00:00 db2ipccm 0
db2inst1 6616 6608 0 21:30 pts/1 00:00:00 db2tcpcm 0
db2inst1 6617 6608 0 21:30 pts/1 00:00:00 db2resync 0
db2inst1 6620 6608 0 21:30 pts/1 00:00:00 db2hmon ,0,0,0,1,0,0,0,0,1e014,2,0,1,9fe0,0x113a0000,0x113a0000,15fc000,58004,2,f800a
db2inst1 6618 6613 0 21:30 pts/1 00:00:00 db2srvlst 0
db2inst1 8502 6613 0 22:50 pts/1 00:00:00 db2agent (instance) 0
db2inst1 8748 6613 0 23:07 pts/1 00:00:00 db2agent (idle) 0
db2inst1 8831 6613 0 23:17 pts/1 00:00:00 db2agent (idle) 0
db2inst1 9026 6613 0 23:27 pts/1 00:00:00 db2agent (idle) 0
db2inst1 9124 6613 0 23:34 pts/1 00:00:00 db2agent (idle) 0
db2inst1 9125 6613 0 23:34 pts/1 00:00:00 db2agent (idle) 0
db2inst1 6873 6615 0 21:46 pts/1 00:00:00 db2agent (instance) 0
[db2inst1@home SQLOGDIR]$ db2 archive log for db fangys
DB20000I The ARCHIVE LOG command completed successfully.
----------------这样就行了，很奇怪