Two Node RAC Database Hang due the MMNL PROCESS WRITING a HUGE TRACE FILE and CONSUMING the FILE SYSTEM
(Doc ID 2798273.1)
Last updated on MAY 12, 2022
Applies to:Oracle Database - Enterprise Edition - Version 126.96.36.199.0 and later
Information in this document applies to any platform.
On : 188.8.131.52.0 version, RDBMS
Two node RAC database hang
We encountered some hang issue on our RAC database.
Just prior to this issue, it seemed that the diag filesystem for that database had filled up to 100%, mainly caused by a 13 GB mmnl trace file with the following content:
kqrhngc ph1: po 0xf7477710 req S from session 0x15c8e5120 lock 0xf25a9210
kqrhngc ph1: blocker #1 owner mode X session 0x160ffd4d0 lock 0x65432220
We purged this tracefile using adrci, but it got re-created immediately again with the same type of contents.
At that point, the database was completely unresponsive, no connection, even "sqlplus / as sysdba" was possible.
As a solution, we killed the pmon process on instance 2. This recovered the situation.
No Database Hang
The issue has the following business impact:
Due to this issue, database hung.
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