OHASD - Oracle High Availability
Services Daemon:
-
It is the first
and only daemon which is going to start by parent init process and in turn it
is responsible for starting some other agents & daemon by reading OLR (oracle
local registry file)
-
It needs access
to OLR file that contains the startup sequence of other child daemons.
CSRD – Cluster Ready Services Daemon:
-
It is responsible
for maintain the cluster configuration and HA (High availability) operations by
reading the OCR file (oracle cluster registry)
-
OCR file contains
the complete cluster information which is required for CRSD Daemon.
CSSD – Cluster Synchronization Services
Daemon:
-
It is responsible
for updating node membershIP of all the nodes within the cluster into VD
(Voting Disk)
-
In Non-RAC
environment, CSSD daemon is responsible for maintaining the communication
between ASM instance and ASM Clients database instances.
VD – Voting Disk:
-
It consist the
updated information of all the cluster nodes.
-
Both OCR & VD
requires 280 MB of space
EVMP – Event Manager Daemon:
It is responsible for publishing & subscribing the
events which are generated by CRSD Daemon to the other nodes
OCTSSD – Oracle Cluster Time Synchronization
Services Daemon:
-
It is responsible
for maintaining the consistency in time
-
It has two modes
o
Observer : if NTP
(network time protocol) is enabled
o
Active : if NTP
is disabled
GMNPD
GSD: From 10g it is duplicated, it is responsible for performing the
administrative tasks whenever GUI application like NETCA or DBCA invoked.
ONS – Oracle Notification Server: It is responsible for publishing the notification
events thru FAN (Fast Application Notifications)
VIP – Virtual IP:
-
It is registered as
a resource into OCR and maintained the status into OCR.
-
For Release 2
onwards, we require every node specific one private IP in one subnet mask and
one public IP & VIP on other subnet mask and 3 unused scan VIP’s on the
same subnet mask of public.
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