检查数据库参数以及操作系统参数。
$ sqlplus / as sysdba
alter system set events ‘10281 trace name context forever, level xxx’; 
– where xxxxxx is the number of seconds to timeout at.
eg: alter system set events ‘10281 trace name context forever, level 300’;

MOS 上这几篇文章可以参考一下。
ID 1379200.1
ID 1345364.1

4节点都出现说明是个共性的问题，有什么变动，为什么重启？

没做什么变更过节回来就发现库挂了，按照1345364.1把kernel.randomize_va_space改成了0，昨天重启了服务器先恢复业务。

alert日志服务器挂掉前的记录：
IPC Receiver dump detected. Sender instance 1 Receiver pnum 121 ospid 237298 [oracle@rac4 (LCK0)], pser 1
2021-02-21T19:49:30.832574+08:00
Errors in file /u01/oracle/app/oracle/diag/rdbms/kxzc/kxzc4/trace/kxzc4_lck0_237298.trc:
2021-02-21T19:50:49.993258+08:00
Instance termination initiated by instance 1 with reason 1.
Instance 1 received a reconfig event from its cluster manager indicating that this instance is supposed to be down
Please check instance 1’s alert log and LMON trace file for more details.
Please also examine the CSS log files.
2021-02-21T19:50:50.062082+08:00
System state dump requested by (instance=4, osid=235728 (LMON)), summary=[abnormal instance termination].
2021-02-21T19:50:50.073845+08:00
LMON (ospid: 235728): terminating the instance due to error 481
2021-02-21T19:50:50.088155+08:00
System State dumped to trace file /u01/oracle/app/oracle/diag/rdbms/kxzc/kxzc4/trace/kxzc4_diag_235623_20210221195050.trc
2021-02-21T19:50:51.470328+08:00
License high water mark = 33
2021-02-21T19:50:55.378085+08:00
ORA-1092 : opitsk aborting process
2021-02-21T19:50:56.306572+08:00
Instance terminated by LMON, pid = 235728
2021-02-21T19:50:56.308939+08:00
Warning: 2 processes are still attach to shmid 950299:
(size: 28672 bytes, creator pid: 231417, last attach/detach pid: 295360)
2021-02-21T19:50:56.471878+08:00
USER (ospid: 294129): terminating the instance
2021-02-21T19:50:56.480057+08:00
Instance terminated by USER, pid = 294129
2021-02-22T10:00:42.724452+08:00
Adjusting the default value of parameter parallel_max_servers
from 10240 to 2450 due to the value of parameter processes (3000)
Starting ORACLE instance (normal) (OS id: 99958)
2021-02-22T10:00:42.803945+08:00
CLI notifier numLatches:131 maxDescs:5068
2021-02-22T10:00:42.807967+08:00

2021-02-22T10:00:42.808101+08:00
Dump of system resources acquired for SHARED GLOBAL AREA (SGA)

2021-02-22T10:00:42.808287+08:00
Per process system memlock (soft) limit = 3072M
2021-02-22T10:00:42.808405+08:00
Expected per process system memlock (soft) limit to lock
SHARED GLOBAL AREA (SGA) into memory: 12G
2021-02-22T10:00:42.808628+08:00
Available system pagesizes:
4K, 2048K
2021-02-22T10:00:42.808817+08:00
Supported system pagesize(s):
2021-02-22T10:00:42.808915+08:00
PAGESIZE AVAILABLE_PAGES EXPECTED_PAGES ALLOCATED_PAGES ERROR(s)
2021-02-22T10:00:42.809018+08:00
4K Configured 7 3145735 NONE
2021-02-22T10:00:42.809258+08:00
2048K 0 6145 0 NONE
2021-02-22T10:00:42.809356+08:00
RECOMMENDATION:
2021-02-22T10:00:42.809479+08:00

1. For optimal performance, configure system with expected number
   of pages for every supported system pagesize prior to the next
   instance restart operation.
   2021-02-22T10:00:42.818052+08:00
2. Increase per process memlock (soft) limit to at least 12GB
   to lock 100% of SHARED GLOBAL AREA (SGA) pages into physical memory
   2021-02-22T10:00:42.818269+08:00

你这日志贴的和你启动的库的时间都不一致，怎么看？