Monday, April 27, 2026

Oracle RAC Cluster Maintenance | RAC Startup Sequence | Startup Troubleshooting Guide | Interview Q&A

Clusterware Maintenance: (Bouncing) & Database Maintenance: (Bouncing) 
======================================================================
HAS -> CRS -> ASM -> DB 

DB: oracle (DEVDB1/DEVDB2)
=== 
Node1:
srvctl status instance -i DEVDB1 -d DEVDB
srvctl stop instance -i DEVDB1 -d DEVDB
srvctl start instance -i DEVDB1 -d DEVDB

sqlplus / as sysdba
shut immediate
startup

Node2:
srvctl status instance -i DEVDB2 -d DEVDB
srvctl stop instance -i DEVDB2 -d DEVDB
srvctl start instance -i DEVDB2 -d DEVDB

sqlplus / as sysdba
shut immediate
startup


Node1 & Node2: Entire DB downtime 
srvctl status database -d DEVDB
srvctl stop database -d DEVDB
srvctl start database -d DEVDB

from both the nodes
sqlplus / as sysdba
shut immediate
startup


ASM: oracle (+ASM1/+ASM2)
====
node1:
srvctl status asm 
srvctl stop asm
srvctl start asm

node2:
srvctl status asm
srvctl stop asm
srvctl start asm


CRS: root (+ASM1/+ASM2)
=====
node1:
crsctl check crs 
crsctl stop crs 
crsctl start crs 

node2:
crsctl check crs 
crsctl stop crs 
crsctl start crs 


HAS: root (+ASM1/+ASM2)
====
node1:
crsctl check has 
crsctl stop has 
crsctl start has 

node2:
crsctl check has 
crsctl stop has 
crsctl start has 


Cluster Start-Up sequence:
==========================
crsctl stop crs/has
crsctl start crs/has

crsctl stat res -t -init 
-> Few cluster resource are not starting 
-> cssd is not coming up 
-> gpnpd is not comping up 

What is the reason? 
- No answer until we check those respective logs 

Question where are these logs?
-> $ORACLE_BASE/diag -> /u01/app/oracle/diag

- cluster resource logs -> /u01/app/oracle/diag/crs (/u01/app/oracle/diag/crs/oraclelab1/crs/trace)
- asm logs -> /u01/app/oracle/diag/asm (/u01/app/oracle/diag/asm/+asm/+ASM1/trace) 
- database logs -> /u01/app/oracle/diag/rdbms (/u01/app/oracle/diag/rdbms/devdb/DEVDB1/trace)
- listener log -> /u01/app/oracle/diag/tnslsnr/oraclelab1


cluster startup troubleshooting 
+++++++++++++++++++++++++++++++++
crsctl stop crs/has
crsctl start crs/has
crsctl stat res -t -init 
- cluster resource logs -> /u01/app/oracle/diag/crs (/u01/app/oracle/diag/crs/oraclelab1/crs/trace)


Cluster StartUp sequence:
==========================
OHAS -> LEVEL1 -> LEVEL2 -> LEVEL3 -> LEVEL4

OHASD -> oracle high availability service 

HAS is not starting? (Oracle High availability service demon) 
- OLR is missing or corrupted  (Oracle local registry) 

cssd / cssdmonitor - cluster synchronization service demon 
CSSD is not starting?
- voting disks are missing or corrupted 

CRSD - cluster ready service 
- read OCR file (Oracle Central registry)

CRSD is not starting?
- OCR is missing or corrupted  (Oracle Central registry) 

What is OLR, OCR, Votedisk?  
where they are located? 

Regards,
Mallikarjun / Vismo Technologies
WhatsApp: +91 9880616848 / +91 9036478079
Cell: +91 9880616848 / +91 9036478079
Email: mallikarjun.ramadurg@gmail.com / vismotechnologies@gmail.com

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