Important RAC logs

https://www.youtube.com/watch?v=U00k1vQrOmg
grid_home/log/host_name/alertrac1.log

writes clusterware stack all importan messages
posts cluster stack/start/stop messages
node eviction messages
OLR events
voting disk and OCR related messages
Active node list
Preferably the fisrt log file to review upon any cluster issues

grid_home/log/host_name/crsd.log

any cluster resources(database.listenr,vip ect)  start/stop/failure occurence are written
Review this log when you have resources failures , unable to start etc
also if you have issues with OCR you can review this logile

grid_home/log/host_name/ocssd.log

cluster sysncronization deamon maintain this log
Busiest lofile
Records Node inter communication messages

Heart beat and missing node eviction messages


grid_home/log/host_name/ohasd
OHASD manitian this log
High availablity service message are written here
review the log when you have issues while running root.sh/rootupgrade.sh
if the service unable to start or becomes unhealthy due to OLR problems
Load default debugging level