An error is reported when executing a command in dmrman (DMAP service background starts normally):

RMAN> BACKUP DATABASE '/dm/dmdbms/data/DAMENG/dm.ini';
BACKUP DATABASE '/dm/dmdbms/data/DAMENG/dm.ini';
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running...[4].
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running...[3].
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running...[2].
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running...[1].
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running...[0].
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running, write dmrman info.
EP[0] max_lsn: 155855
BACKUP DATABASE [DAMENG], execute......
os_pipe2_conn_server open failed, name:[/dm/dm_bak/DM_PIPE_DMAP_LSNR_WR], errno:2
CMD END.CODE:[-7109],DESC:[Pipe connect failure]
[-7109]:Pipe connect failure
RMAN>

resolvent:

Method (1)

Must go to DM_ Execute dmrman in the home/bin directory. Although the environment variable is configured to recognize the dmrman command, an error will be reported during execution. It is speculated that the files relied on during program execution cannot be recognized correctly. Switch to $DM_ Home/bin solves this problem.

[[email protected] bin]$ pwd
/dm/dmdbms/bin
[[email protected] bin]$ ./dmrman
dmrman V7.6.0.95-Build(2018.09.13-97108)ENT 
RMAN> BACKUP DATABASE '/dm/dmdbms/data/DAMENG/dm.ini' FULL BACKUPSET '/dm/dm_bak/db_full_bak_01';
BACKUP DATABASE '/dm/dmdbms/data/DAMENG/dm.ini' FULL BACKUPSET '/dm/dm_bak/db_full_bak_01';
file dm.key not found, use default license!
Global parameter value of RT_HEAP_TARGET is illegal, use min value!
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running...[4].
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running...[3].
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running...[2].
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running...[1].
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running...[0].
checking if the database under system path [/dm/dmdbms/data/DAMENG] is running, write dmrman info.
EP[0] max_lsn: 116978
BACKUP DATABASE [DAMENG], execute......
CMD CHECK LSN......
BACKUP DATABASE [DAMENG], collect dbf......
CMD CHECK ......
DBF BACKUP SUBS......
total 1 packages processed...
total 3 packages processed...
total 4 packages processed...
DBF BACKUP MAIN......
BACKUPSET [/dm/dm_bak/db_full_bak_01] END, CODE [0]......
META GENERATING......
total 5 packages processed...
total 5 packages processed!
CMD END.CODE:[0]
backup successfully!
time used: 7081.941(ms)
RMAN>

Method (2)

An error is reported in the log. The pipeline file already exists. An error is reported after deleting the pipeline file OS_ pipe2_ Server open failed, check whether the data is written without permission, modify the permission, and then report an error. The pipeline connection timed out
use./dmrman use_ AP = 2 restore without pipeline DMAP succeeded.