1.157 INSTANCE_MODE
INSTANCE_MODE
indicates whether the instance is read-write, read-only, or read-mostly.
Property | Description |
---|---|
Parameter type |
String |
Syntax |
|
Default value |
|
Modifiable |
No |
Basic |
No |
Oracle RAC |
See the Oracle RAC restrictions in the initialization parameter description below. |
A READ-WRITE
instance is a regular Oracle instance.
A READ-ONLY
instance is an Oracle instance that can only be opened in read-only mode.
A READ-MOSTLY
instance is an Oracle instance that performs very few database writes.
These restrictions apply when setting the parameter on different Oracle Real Application Clusters (Oracle RAC) instances:
-
There must be at least one instance alive with
INSTANCE_MODE
set toREAD-WRITE
at any given time. If the only instance withINSTANCE_MODE
set toREAD-WRITE
goes down, all other instances will be brought down by Oracle automatically. -
An instance with
INSTANCE_MODE
set toREAD-ONLY
cannot be the first instance to open a database or any pluggable database (PDB) among all instances in an Oracle RAC cluster. -
Oracle does not support co-existence of an instance with
INSTANCE_MODE
set toREAD-ONLY
and an instance withINSTANCE_MODE
set toREAD-MOSTLY
in the same Oracle RAC cluster.