[error reporting]

SQL> backup database backupset 'dm3bak01';
backup database backupset 'dm3bak01';
[-7169]:bakres failed to communicate with DMAP message.
Used time: 00:00:10.033. execution number:0.

[log content]

2022-04-27 09:08:01 [CMD] database P0000048762 PPID4294967295  backup database backupset 'dm3bak01';


2022-04-27 09:08:01 [CMD] database P0000048762 PPID4294967295  BACKUP DATABASE [dm03]
2022-04-27 09:08:01 [INFO] database P0000048762  PPID4294967295  CMD START....
2022-04-27 09:08:01 [INFO] database P0000048762  PPID4294967295  BACKUP DATABASE [dm03],execute......
2022-04-27 09:08:01 [INFO] database P0000048762  PPID4294967295  check limits of huge data
2022-04-27 09:08:01 [INFO] database P0000048762  PPID4294967295  CMD CHECK LSN ......
2022-04-27 09:08:01 [INFO] database P0000048762  PPID4294967295  adjust checkpoint lsn to maximal apply lsn 0
2022-04-27 09:08:11 [INFO] database P0000048762  PPID4294967295  connect to dmap with portnum[4236], tsk_num: [4], code: [-7169].
2022-04-27 09:08:11 [WARNING] database P0000048762  PPID4294967295  CMD END.CODE:[-7169], DESC:[bakres fails to communicate with DMAP messages], COST:[00:00:10]

[reason for error reporting]
because dmapservice is not started or there is a problem with dmapservice

[problem handling]

[pwd:/u01/dm8/dmdbms/bin]$ ./DmAPService start
DmAPService (pid 101899) is running.    # I find it is started

[pwd:/u01/dm8/dmdbms/bin]$ ./DmAPService restart    # try to restart
Stopping DmAPService:                                      [ OK ]
Starting DmAPService:                                      [ OK ]

[pwd:/u01/dm8/dmdbms/bin]$ !disql
SQL> backup database backupset 'dm3bak01';      # backup successfully
The operation has been executed
Time used: 00:00:03.660. Execution number: 55700.