weekfri_full_bak 应该是这个备份集名称已经存在

[dmdba@localhost:/dmdb8/dmtmp]$ disql sysdba:5237
password:

Server[LOCALHOST:5237]:mode is normal, state is open
login used time : 4.077(ms)
disql V8
SQL> backup database to weekfri_full_bak backupset '/dmdb8/dmtmp/db_full_bak_03';
backup database to weekfri_full_bak backupset '/dmdb8/dmtmp/db_full_bak_03';
[-8234]:backup name conflicts.
used time: 00:00:03.805. Execute id is 0.

--解决办法
测试环境/生产环境可删除默认备份路径下文件再次备份或更改备份名字(若删除一定要谨慎)

1.定位dm.ini配置文件位置
[root@localhost dmtmp]# ps -ef | grep server
dmdba       967      1  0 10:16 ?        00:00:31 /dmdb8/dmdbms/bin/dmserver path=/dmdb8/dmdata/fuwa/dm.ini -noconsole

2.查看dm.ini配置文件中BAK_PATH参数
[root@localhost dmtmp]# vi /dmdb8/dmdata/fuwa/dm.ini
BAK_PATH                        = /dmdb8/dmdata/fuwa/bak

3.查看并删除默认备份路径下文件
[root@localhost dmtmp]# cd /dmdb8/dmdata/fuwa/bak
[root@localhost bak]# ls -l
total 0
drwxr-xr-x 2 dmdba dinstall 87 Oct 17 15:38 db_full_bak_02

[root@localhost dmtmp]# cd /dmdb8/dmdata/fuwa/bak
[root@localhost bak]# rm -rf *

4.再次备份，备份成功
SQL> backup database to weekfri_full_bak backupset '/dmdb8/dmtmp/db_full_bak_03';
executed successfully
used time: 00:00:03.102. Execute id is 3401.

已解决