There are 2 ways we can do it as short and detail version .
Short startup sequence :
1) OS
2) Cluster
3) ASM
4) INSTANCE
5) Listener
6) Service
Detail explained is as below :
There are 4 Layers to the architecture of oracle as shown in below diagram
Credit source for diagram Internet .
Or : Simple One
Now lets get started with the demons by their startup sequence:
Demons :
1) INIT : INIT is the very first file to be checked to be start at the time of the operating system boot,it is system and service manager for the Linux , Aix or any other Linux flavor. This service start and stop through script which is stored in the /etc/init.d directory .
2) CRSD : The CRS daemon (crsd) manage cluster resource based on the configuration information stored in the OCR for each resource.
Is responsible for the start,stop monitor and failover of resource it maintain OCR and also restart the resource when the failover occurs ,
this applicable for RAC system . For standalone configuration OHASD is used
Sequence :
INIT –> INIT.OHASD –> OHASD –> CRSD [REBOOT]
3) Cluster synchronization service [CSS] :
I) CSSD monitor — Mandate : Monitor for the node hang & subsequently act as oprocd – which act as I/O fencing and also monitors Ocssd [ via oclsomon] . This is a multithread process and runs with an elevated priority
Sequence :
INIT –> INIT.OHASD –> OHASD –> OHASD.bin –> CSSD monitor
II) CSSD Agent : This process is spawned by ohasd process responsible for I/O fencing
Killing of process would cause node reboot , Also check the status ocssd.bin demon
Sequence :
INIT –> INIT.OHASD –> OHASD –> OHASD.bin –> CSSD agent –> OCSSD
III) OCSSD.bin : This process manages the cluster node membership , failure of this process can cause node restart
Sequence :
INIT –> INIT.OHASD –> OHASD –> OHASD.bin –> CSSD agent –> OCSSD –> OCSSD.bin
4) EVMD :
I) EVMD.bin
II) EVMlogger.bin
III) EVMlogger.log
I) EVMD.bin : Distributes & communicates cluster events to all of the cluster member so that they are aware of the changes being done in the cluster
II) EVMlogger.bin : Started by the evmd.bin reads the config file and determine the events to subscribe from evmd and it runs user defined reactions to those events
5) Ora root agent : This is a specialized oraagent process which helps CRSD manage resouces owner by root e.g : Network , Node VIP , SCAN IP
6) CTSSD : The cluster time synchronization service process provides time synchronization for the cluster in the absence in the ntpd . if ntpd is configured , ctssd will run in observer mode.
7) Cluster Logger Service : This Logger receives information from all nodes in the cluster & persist CHM repository based on the database this service runs on only 2 nodes in cluster
Cluster logger service receives the os metric collection
information from all the nodes and kept it in the Cluster Health Monitor (CHM) repository ,
which received from the osysmond service. These is only one cluster logger service (loggerd)
run on entire cluster any other node is selected as standby for the master logger service.
Master process manage the OS metrics data which is in CHM repository and manage the replica of the metrics information on the standby.
8) OSYSMOND : This process is responsible for monitoring and operating system metrics collection that sends data to cluster logger service
Service run on all node in the cluster. This process send the all metric data to the cluster logger service ologgerd
9) GPNPD : This is a small XML file containing information such as
I) Cluster name
II) Location of VOTE disk
III) Network Information
IV) SPfile information for ASM
This file is individual for all nodes .If the node is already part of cluster agent reads the existing profile on the node. If node is being added to the cluster GPNP agent locates agent on the other existing nodes using multicast protocol and gets the profile from other agent nodes
