今天，一同事在自己的虚拟机上安装oracle 19c rac集群，在他安装的过程中遭遇了报错：
PRCR-1079&CRS-5017&ORA-03113。具体的报错信息截图如下：
看着像是功败垂成的样子，同事提供的DBCA报错日志信息提示，数据库库实例未启动：
进一步跟踪两个节点db实例的告警日志，除了实例被PMON进程终止，未发现其他有价值的信息：
实例1的告警日志：
2021-02-20T11:45:14.671691+08:00
Dumping diagnostic data in directory=[cdmp_20210220114514], requested by (instance=2, osid=88420 (PMON)), summary=[abnormal instance termination].
2021-02-20T11:45:39.728434+08:00
ALTER SYSTEM SET _ipddb_enable=TRUE SCOPE=MEMORY SID='racdb1';
2021-02-20T11:46:15.464253+08:00
Process termination requested for pid 91909 [source = rdbms], [info = 2] [request issued by pid: 91857, uid: 6001]
2021-02-20T11:46:23.515236+08:00
Warning: VKTM detected a forward time drift.
Please see the VKTM trace file for more details:
/oracle/app/oracle/diag/rdbms/racdb/racdb1/trace/racdb1_vktm_91812.trc
实例2的告警日志：
2021-02-20T11:44:03.379475+08:00
My CSS node number is 2
My CSS hostname is racdb62
Instance reconfiguration: current system load 19 (hiload)
lmon registered with NM - instance number 2 (internal mem no 1)
2021-02-20T11:45:14.511978+08:00
PMON (ospid: ): terminating the instance due to ORA error
2021-02-20T11:45:14.545360+08:00
System state dump requested by (instance=2, osid=88420 (PMON)), summary=[abnormal instance termination]. error - 'Instance is terminating.'
System State dumped to trace file /oracle/app/oracle/diag/rdbms/racdb/racdb2/trace/racdb2_diag_88450.trc
2021-02-20T11:45:14.568799+08:00
Cause - 'Instance is being terminated due to fatal process death (pid: 22, ospid: 88564, LMON)'
2021-02-20T11:45:26.851684+08:00
License high water mark = 1
2021-02-20T11:45:28.491267+08:00
Dumping diagnostic data in directory=[cdmp_20210220114514], requested by (instance=2, osid=88420 (PMON)), summary=[abnormal instance termination].
2021-02-20T11:45:30.181664+08:00
Instance terminated by PMON, pid = 88420
2021-02-20T11:45:31.276108+08:00
Warning: 2 processes are still attacheded to shmid 5:
(size: 16384 bytes, creator pid: 87669, last attach/detach pid: 88626)
2021-02-20T11:45:32.234979+08:00
USER(prelim) (ospid: 89675): terminating the instance
2021-02-20T11:45:32.236231+08:00
Instance terminated by USER(prelim), pid = 89675
但是，看到ORA-27101告警，下意识的感觉是集群操作系统配置或者oracle用户的环境变量有问题。
2021-02-20 11:45:33.445 :CLSDYNAM:1644160768: [ora.racdb.db]{1:60322:3769} [check] ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
Linux-x86_64 Error: 2: No such file or directory
Additional information: 4376
Additional information: -907856465
Process ID: 0
Session ID: 0 Serial number: 0
同事提供的两个节点的oracle用户环境变量，经检查没问题：
排除掉环境变量配置问题后，那就可能是主机配置问题，同事提供了sysctl.conf配置内容：
看到kernel.shmmax配置为4G左右，貌似看到问题根源，接下来询问同事虚机的内存配置，配置为6.3G：
oracle 19c rac集群安装的最低配置要求为：
总结：ORACLE 19C RAC集群安装由于内存6.3G不足以满足grid和db内存的实例化要求，导致dbca建库报错
PRCR-1079&CRS-5017&ORA-03113。