In this Document
APPLIES TO:Oracle Database Cloud Schema Service - Version N/A and laterOracle Database Exadata Express Cloud Service - Version N/A and later Oracle Database Exadata Cloud Machine - Version N/A and later Oracle Database Cloud Exadata Service - Version N/A and later Oracle Database Backup Service - Version N/A and later Information in this document applies to any platform. SYMPTOMSOn : 12.1.0.2 version, RDBMSDatabase crashed and the following error observed in the alert log file.
ERROR
----------------------- Thu Nov 16 20:31:48 2017 Warning: VKTM detected a time drift. Time drifts can result in an unexpected behavior such as time-outs. Please check trace file for more details. Thu Nov 16 20:31:49 2017 Instance Critical Process (pid: 6, ospid: 16813, MMAN) died unexpectedly Thu Nov 16 20:31:49 2017 System state dump requested by (instance=1, osid=16803 (PMON)), summary=[abnormal instance termination]. System State dumped to trace file /apps/oracle/diag/rdbms/<dbname>/<instance_name>/trace/<instance_name>_diag_16817_20171116203149.trc Thu Nov 16 20:31:49 2017 PMON (ospid: 16803): terminating the instance due to error 822 CHANGESCAUSEThe collected OS error log shows "Out of memory" and "Free swap = 0kB" errors, and it proved that mman process got killed due to "Out of memory" problem:
Nov 16 20:31:45 <osname> kernel: Free swap = 0kB <<< Free swap = 0kB
Nov 16 20:31:45 <osname> kernel: Out of memory: Kill process 16813 (ora_mman_<instance_name>) score 112 or sacrifice child <<< Out of memory SOLUTIONEngage OS admin to investigate the memory shortage problem.The OOM killer, a feature enabled by default, is a self protection mechanism employed by the Linux kernel when under severe memory pressure. Please refer the below document for more details:
Linux: Out-of-Memory (OOM) Killer (Doc ID 452000.1)
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