Hi,
Sometimes You can get “TNS-12615: TNS:preempt error ” error.
Details of error are as follows.
TNS-12615: TNS:preempt error
Cause: A request to service an event failed because no event notification has yet been posted.
Action: Not normally visible to the user. For further details, turn on tracing and reexecute the operation.
If error persists, contact Oracle Customer Support.
This error is related with the Too many concurrent connection requests.
Increase the queuesize as follows.
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.63.34)(PORT = 1521)(QUEUESIZE=1000))
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
)
)
Or Second case related with this error is as follows.
The issue is related to load and overhead related to Automatic Diagnostic Repository (ADR) functionality and IO issues on the database server. The combination of these results in slowness in spawning the database shadow processes, causing number of connection requests to be queued by the TNS Listener and internal limits restrictions to be reached.
Each new shadow process that is spawned tries to create the ADR directories, even if they already exist.
This is due to Unpublished Bug:9700115 CHECK ADR DIRECTORIES EXISTENCE AND ATTRIBUTES FIRST BEFORE CREATING THEM
As a workaround, set the following initialization parameter for the 11g Database instance(s) to disable the Automatic Diagnostic Repository (ADR) mechanism.
_diag_adr_enabled=FALSE
and/or:
Apply Patch:9700115 to change the behavior of the ADR to check if the subdirectories exists before it tries to create them.
Do you want to learn more details about RMAN, then read the following articles.
https://ittutorial.org/rman-backup-restore-and-recovery-tutorials-for-beginners-in-the-oracle-database/