I have installed 2 oracle 19.3 databases instances on the same server.

The first installed DB instance one has the following specifications :

[oracle@ora19 ~]$ echo $ORACLE_HOME /u01/app/oracle/product/19.0.0/db_1 [oracle@ora19 ~]$ echo $ORACLE_SID oradb 

I can connect to this one whitout problem :

sqlplus / as sysdba SQL*Plus: Release 19.0.0.0.0 - Production on Fri Nov 25 08:31:37 2022 Version 19.3.0.0.0 Copyright (c) 1982, 2019, Oracle. All rights reserved. Connecte a : Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production Version 19.3.0.0.0 SQL> 

The second installed DB instance one has the following specifications :

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[oracle@ora19 bin]$ echo $ORACLE_HOME /u01/app/oracle/product/19.0.0/rman/ [oracle@ora19 bin]$ echo $ORACLE_SID rmandb 

I am encountering an ORA-12547 error when I try to connect to this DB :

[oracle@ora19 bin]$ ./sqlplus / as sysdba SQL*Plus: Release 19.0.0.0.0 - Production on Fri Nov 25 08:32:23 2022 Version 19.3.0.0.0 Copyright (c) 1982, 2019, Oracle. All rights reserved. ERROR: ORA-12547: TNS:lost contact Enter user-name: 

The 2 databases process are running as usually :

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[oracle@ora19 bin]$ ps -edf | grep 'pmon\|lgr\|ckpt' grid 3167 1 0 nov.24 ? 00:00:03 asm_pmon_+ASM grid 3197 1 0 nov.24 ? 00:00:02 asm_ckpt_+ASM oracle 3295 1 0 nov.24 ? 00:00:04 ora_pmon_oradb oracle 3349 1 0 nov.24 ? 00:00:15 ora_ckpt_oradb oracle 12154 5055 0 08:39 pts/0 00:00:00 grep --color=auto pmon\|lgr\|ckpt oracle 24177 1 0 nov.24 ? 00:00:04 ora_pmon_rmandb oracle 24217 1 0 nov.24 ? 00:00:16 ora_ckpt_rmandb 

idem with srvctl check:

[oracle@ora19 bin]$ srvctl status database -db rmandb 

=> ok

[oracle@ora19 bin]$ srvctl status database -db oradb 

=> ok

listener status:

[oracle@ora19 bin]$ lsnrctl status LSNRCTL for Linux: Version 19.0.0.0.0 - Production on 25-NOV-2022 09:07:50 Copyright (c) 1991, 2019, Oracle. All rights reserved. Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521)) STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for Linux: Version 19.0.0.0.0 - Production Start Date 24-NOV-2022 13:04:31 Uptime 0 days 14 hr. 3 min. 19 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Listener Parameter File /u01/app/19.0.0/grid/network/admin/listener.ora Listener Log File /u01/app/grid/diag/tnslsnr/ora19/listener/alert/log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=ora19.localdomain)(PORT=1521))) (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521))) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcps)(HOST=ora19.localdomain)(PORT=5500))(Security=(my_wallet_directory=/u01/app/oracle/product/19.0.0/db_1/admin/oradb/xdb_wallet))(Presentation=HTTP)(Session=RAW)) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcps)(HOST=ora19.localdomain)(PORT=5501))(Security=(my_wallet_directory=/u01/app/oracle/admin/rmandb/xdb_wallet))(Presentation=HTTP)(Session=RAW)) Services Summary... Service "+ASM" has 1 instance(s). Instance "+ASM", status READY, has 1 handler(s) for this service... Service "+ASM_DATADG" has 1 instance(s). Instance "+ASM", status READY, has 1 handler(s) for this service... Service "+ASM_FRADG" has 1 instance(s). Instance "+ASM", status READY, has 1 handler(s) for this service... Service "+ASM_OCRDG" has 1 instance(s). Instance "+ASM", status READY, has 1 handler(s) for this service... Service "+ASM_RMANDG" has 1 instance(s). Instance "+ASM", status READY, has 1 handler(s) for this service... Service "oradb.localdomain" has 1 instance(s). Instance "oradb", status READY, has 1 handler(s) for this service... Service "oradbXDB.localdomain" has 1 instance(s). Instance "oradb", status READY, has 1 handler(s) for this service... Service "rmandb.localdomain" has 1 instance(s). Instance "rmandb", status READY, has 1 handler(s) for this service... Service "rmandbXDB.localdomain" has 1 instance(s). Instance "rmandb", status READY, has 1 handler(s) for this service... The command completed successfully 

Are there special considerations when running 2 oracle instances on the same machine ?