INIT PARAMETERS
NEEDED FOR RAC
The following Init parameters are needed in a RAC database.
1) active_instance_count:-
Property
|
Description
|
Parameter type
|
Integer
|
Default value
|
There is no default value.
|
Modifiable
|
No
|
Range of values
|
1 or >= the number of instances
in the cluster. (Values other than 1 have no effect on the active or standby
status of any instances.)
|
Basic
|
No
|
Real Application Clusters
|
You must set this parameter for
every instance, and multiple instances must have the same value.
|
ACTIVE_INSTANCE_COUNT enables you to designate one instance in a two-instance cluster
as the primary instance and the other instance as the secondary instance. This
parameter has no functionality in a cluster with more than two instances.
When you set this parameter to 1, the first instance you start
up becomes the primary instance and accepts client connections. The second
instance starts up as a secondary instance and can accept client connections
only if the first instance fails. In such an event, the secondary instance becomes
the primary instance.
When the failed instance can once again be started up, it starts
up as the secondary instance, and will not accept client connections unless the
current primary instance fails.
2) cluster_database:-
Property
|
Description
|
Parameter type
|
Boolean
|
Default value
|
false
|
Modifiable
|
No
|
Range of values
|
true | false
|
Basic
|
Yes
|
Real Application Clusters
|
For all instances, the value
must be set to TRUE.
|
CLUSTER_DATABASE is a Real Application Clusters parameter that
specifies whether or not Real Application Clusters is enabled.
3)
cluster_database_instances:-
Property
|
Description
|
Parameter type
|
Integer
|
Default value
|
1
|
Modifiable
|
No
|
Range of values
|
Any nonzero value
|
Basic
|
No
|
Real Application Clusters
|
Multiple instances must have
the same value.
|
CLUSTER_DATABASE_INSTANCES is a Real Application Clusters parameter
that specifies the number of instances that are configured as part of your
cluster database. You must set this parameter for every instance. Normally you
should set this parameter to the number of instances in your Real Application
Clusters environment. A proper setting for this parameter can improve memory
use.
Oracle uses the value of this parameter to compute the default value of
the LARGE_POOL_SIZE parameter when the PARALLEL_AUTOMATIC_TUNING parameter
is set to true. Note that the PARALLEL_AUTOMATIC_TUNIG parameter
has been deprecated.
4)
cluster_interconnects:-
Property
|
Description
|
Parameter type
|
String
|
Syntax
|
CLUSTER_INTERCONNECTS = ifn [: ifn ]
...
|
Default value
|
There is no default value.
|
Modifiable
|
No
|
Range of values
|
One or more IP addresses,
separated by colons
|
Basic
|
No
|
CLUSTER_INTERCONNECTS provides Oracle with information about
additional cluster interconnects available for use in Real Application Clusters
environments.
The CLUSTER_INTERCONNECTS parameter can be used to override
the default interconnect with a preferred cluster traffic network. This
parameter is useful in Data Warehouse systems that have reduced availability
requirements and high interconnect bandwidth demands. You can also use CLUSTER_INTERCONNECTS to
override the default interconnect chosen by Oracle.
For example, if you are running two instances of Oracle for two
databases on the same machine, then you can load balance the interconnect
traffic to different physical interconnects. This does not reduce Oracle
availability.
CLUSTER_INTERCONNECTS can be used in Oracle Real Application
Clusters environments to indicate cluster interconnects available for use for
the database traffic. Use this parameter if you need to override the default
interconnect configured for the database traffic, which is stored in the
cluster registry. This procedure also may be useful with Data Warehouse systems
that have reduced availability requirements and high interconnect bandwidth demands.
CLUSTER_INTERCONNECTS specifically overrides the following:
- Network
classifications stored by oifcfg in the OCR.
- The
default interconnect chosen by Oracle.
If you want to load-balance the interconnect, then Oracle recommends
that you use link-bonding at the operating system level, even if you have two
databases on the same server, so that multiple interconnects use the same
address. Note that multiple private addresses provide load balancing, but do
not provide failover unless bonded. If you specify multiple addresses in
init.ora using CLUSTER_INTERCONNECTS, instead of bonding multiple
addresses at the operating system level, then typically availability is
reduced, because each network interface card failure will take down that
instance.
Refer to your vendor documentation for information about bonding
interfaces. Some vendor bonding architectures may require the use of this
parameter.
If you have multiple database instances on Oracle Real Application
Clusters nodes and want to use a specific interface for each instance, then you
can set theCLUSTER_INTERCONNECTS initialization parameter to the IP
address for each database instance. For example:
hr1.init.ora.cluster_interconnects="192.0.2.111"
oltp3.init.ora.cluster_interconnects="192.0.2.112"
If the Oracle RAC interconnect is configured to run on a different
interface than the Oracle Clusterware interconnect, then this configuration can
cause reduced availability, as failovers or instance evictions can be delayed
if the Oracle RAC interconnect fails while the Oracle Clusterware NIC remains
up.
5)
instance_groups:-
Property
|
Description
|
Parameter type
|
String
|
Syntax
|
INSTANCE_GROUPS = group_name [, group_name ]
...
|
Default value
|
There is no default value.
|
Modifiable
|
No
|
Range of values
|
One or more instance group
names, separated by commas
|
Basic
|
No
|
Real Application Clusters
|
Multiple instances can have
different values.
|
INSTANCE_GROUPS is a Real Application Clusters parameter that you
can specify only in parallel mode. Used in conjunction with the PARALLEL_INSTANCE_GROUP parameter,
it lets you restrict parallel query operations to a limited number of
instances.
This parameter specifies one or more instance groups and assigns the
current instance to those groups. If one of the specified groups is also
specified in the PARALLEL_INSTANCE_GROUP parameter, then Oracle
allocates query processes for a parallel operation from this instance.
6)
instance_number:-
Property
|
Description
|
Parameter type
|
Integer
|
Default value
|
Lowest available number;
derived from instance start up order and INSTANCE_NUMBER value of
other instances. If not configured for Real Application Clusters, then 0.
|
Modifiable
|
No
|
Range of values
|
1 to maximum number of
instances specified when the database was created
|
Basic
|
Yes
|
Real Application Clusters
|
You must set this parameter for
every instance, and all instances must have different values.
|
INSTANCE_NUMBER is a Real Application Clusters parameter that can
be specified in parallel mode or exclusive mode. It specifies a unique number
that maps the instance to one free list group for each database object created
with storage parameter FREELIST GROUPS.
The INSTANCE parameter of the ALTER TABLE ... ALLOCATE
EXTENT statement assigns an extent to a particular free list group. If you
set INSTANCE_NUMBER to the value specified for the INSTANCE parameter,
the instance uses that extent for inserts and for updates that expand rows.
The practical maximum value of this parameter is the maximum number of
instances specified in the CREATE DATABASE statement. The absolute
maximum is operating system-dependent.
7)
lock_name_space:-
Property
|
Description
|
Parameter type
|
String
|
Syntax
|
LOCK_NAME_SPACE = namespace
|
Default value
|
There is no default value.
|
Modifiable
|
No
|
Range of values
|
Up to 8 alphanumeric
characters. No special characters allowed.
|
Basic
|
No
|
LOCK_NAME_SPACE specifies the namespace that the distributed lock
manager (DLM) uses to generate lock names. Consider setting this parameter if a
standby or clone database has the same database name on the same cluster as the
primary database.
If the standby database resides on the same file system as the primary
database, then set LOCK_NAME_SPACE in the standby parameter file to a
distinct value such as the following:
LOCK_NAME_SPACE = standby
8)
parallel_instance_group:-
Property
|
Description
|
Parameter type
|
String
|
Syntax
|
PARALLEL_INSTANCE_GROUP = group_name
|
Default value
|
A group consisting of all
instances currently active
|
Modifiable
|
ALTER SESSION, ALTER
SYSTEM
|
Range of values
|
Any group name specified in the INSTANCE_GROUPS parameter
of any active instance
|
Real Application Clusters
|
Multiple instances can have
different values.
|
PARALLEL_INSTANCE_GROUP is a Real Application Clusters parameter
that you can specify in parallel mode only. Used in conjunction with the INSTANCE_GROUPS parameter,
it lets you restrict parallel query operations to a limited number of
instances.
This parameter identifies the parallel instance group Oracle will use
for spawning parallel execution processes. Parallel operations will spawn
parallel execution processes only on instances that specify a matching group in
their INSTANCE_GROUPS parameter.
If the value of PARALLEL_INSTANCE_GROUP does not correspond to
an instance group name specified for an active instance, Oracle returns an
error.
9)
parallel_server:-
Parameter type:
|
Boolean
|
Parameter
class:
|
Static
|
Default
value:
|
FALSE
|
Range
of values:
|
TRUE | FALSE
|
Oracle
Parallel Server:
|
Multiple
instances must have the same value.
|
PARALLEL_SERVER is
an Oracle Parallel Server parameter that specifies whether Oracle Parallel
Server is enabled.
10)
parallel_server_instances:-
Parameter
type:
|
Integer
|
Parameter
class:
|
Static
|
Default
value:
|
1
|
Range
of values:
|
Any
non-zero value
|
PARALLEL_SERVER_INSTANCES is
an Oracle Parallel Server parameter that specifies the number of instances
currently configured. You must set this parameter for every instance. Normally
you should set this parameter to the number of instances in your Oracle
Parallel Server environment. A proper setting for this parameter can improve
memory use.
Oracle
uses the value of this parameter to compute the default value of the LARGE_POOL_SIZE parameter
when the PARALLEL_AUTOMATIC_TUNING parameter is set to TRUE.
11)
thread:-
Property
|
Description
|
Parameter type
|
Integer
|
Default value
|
0
|
Modifiable
|
No
|
Range of values
|
0 to the maximum
number of enabled threads
|
Real Application
Clusters
|
If specified,
multiple instances must have different values.
|
THREAD is a Real Application Clusters parameter
that specifies the number of the redo thread to be used by an instance.When you create a database, Oracle creates and enables thread 1 as a public thread (one that can be used by any instance). You must create and enable subsequent threads using the
ADD
LOGFILE THREAD clause
andENABLE THREAD clause of the ALTER
DATABASE statement.
The number of threads you create is limited by the MAXINSTANCES parameter specified in the CREATE
DATABASE statement.In exclusive mode, thread 1 is the default thread. However, you can specify
THREAD for an instance running in exclusive
mode if you want to use the redo log files in a thread other than thread 1.In
parallel mode, you can specify any available redo thread number, as long as that
thread number is enabled and is not in use by another instance.A value of zero specifies that this instance can use any available, enabled public thread.
