Transcript Intro to the Class

RAC Networking, Failover, and
Load Balancing
Setting up failover, load balancing, TAF and FCF
Objectives
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At the end of this module the student will
understand the following tasks and concepts.
Understand how Oracle Net interacts with
RAC.
Understand how to configure tnsnames for
RAC with Transparent Application Failover
(TAF)
Understand how to configure JDBC
connections for RAC
Understand how to configure Fast Connection
Failover as an alternative to RAC
Overview
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The Listener
Configuration Files
Oracle Net and RAC
Connect-Time Failover
TAF Failover
Load Balancing
JDBC Configuration for Failover and Load
Balancing
Fast Connection Failover
Listener
Node 1
Database
Client
Node 2
Listener
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Resides on the server
Listens for incoming client connection requests
Manages the traffic to the server; when a client
requests a network session with a server, the
listener actually receives the request and
brokers the client request
If the client's information matches the listener's
information, then the listener grants a connection
to the server.
listener.ora
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Configuration file for the listener process. Identifies:
 The listener name
 Protocol addresses that it will accept connection
requests on
 Services for which it is listening
Typically resides in the
%ORACLE_HOME%\network\admin directory on
Windows NT.
tnsnames.ora
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Configuration file that determines how you
connect to the database.
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Connect to specific instance
Load Balancing
Connect Time Failover
TAF Client Failover
Must be present on server and “thick” clients
(ODBC and JDBC “thick” OCI driver)
Oracle Net and RAC
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Oracle Net understands RAC
Is used to set up the cluster behavior
Supports multiple modes
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Connect-Time Failover
Load Balancing
TAF
Connect-Time Failover
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One service
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Tries one node
then the other node
Used for failover
Balance is done manually
In the event of a failure
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Transaction is lost
Session is lost
Reconnection occurs automatically
Connect-Time Failover
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TESTA1 =
(DESCRIPTION=
(ADDRESS_LIST=
(LOAD_BALANCE=OFF)
(FAILOVER=ON)
(ADDRESS=(PROTOCOL=TCP)(HOST=oradb1)(PORT=1521))
(ADDRESS=(PROTOCOL=TCP)(HOST=oradb2)(PORT=1521)))
(CONNECT_DATA=
(SERVICE_NAME=TESTA)
)
)
TESTA2 =
(DESCRIPTION=
(ADDRESS_LIST=
(LOAD_BALANCE=OFF)
(FAILOVER=ON)
(ADDRESS=(PROTOCOL=TCP)(HOST=oradb2)(PORT=1521))
(ADDRESS=(PROTOCOL=TCP)(HOST=oradb1)(PORT=1521)))
(CONNECT_DATA=
(SERVICE_NAME=TESTA)
)
)
Failover - Backup
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Pairs of services
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The first service defines the second as its backup
The second service defines the first service as its backup
Used for RAC failover
Balance is done manually
In the event of a failure
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Transaction is lost
Session is maintained
Queries are restarted
Reconnection occurs automatically
Failover – Backup
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TESTA1 =
(DESCRIPTION =
(ENABLE = BROKEN)
(LOAD_BALANCE = off)
(FAILOVER = on)
(ADDRESS = (PROTOCOL = TCP)(HOST = oradb1)(PORT = 1523))
(CONNECT_DATA =
(SERVICE_NAME = TESTA)
(INSTANCE_NAME = TESTA1)
(FAILOVER_MODE =
(BACKUP = TESTA2)
(TYPE = SELECT)
(METHOD = BASIC)
(RETRIES = 120)
(DELAY = 5))))
TESTA2 =
(DESCRIPTION =
(ENABLE = BROKEN)
(LOAD_BALANCE = off)
(FAILOVER = on)
(ADDRESS = (PROTOCOL = TCP)(HOST = oradb2)(PORT = 1523))
(CONNECT_DATA =
(SERVICE_NAME = TESTA)
(INSTANCE_NAME = TESTA2)
(FAILOVER_MODE =
(BACKUP = TESTA1)
(TYPE = SELECT)
(METHOD = BASIC)
(RETRIES = 120)
(DELAY = 5))))
Failover - Preconnect
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Pairs of services
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The first service defines the second as its backup
The second service defines the first service as its backup
Both services preconnect to their backup when the primary
connections are made
Used for RAC failover
Balance is done manually
In the event of a failure
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Transaction is lost
Session is maintained
Queries are restarted
Connection is quickly switched over to the preconnected backup
Failover - Preconnect
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TESTA1 =
(DESCRIPTION =
(ENABLE = BROKEN)
(LOAD_BALANCE = off)
(FAILOVER = on)
(ADDRESS = (PROTOCOL = TCP)(HOST = oradb1-vip)(PORT = 1523))
(CONNECT_DATA =
(SERVICE_NAME = TESTA)
(INSTANCE_NAME = TESTA1)
(FAILOVER_MODE =
(BACKUP = TESTA2)
(TYPE = SELECT)
(METHOD = PRECONNECT)
(RETRIES = 120)
(DELAY = 5))))
TESTA2 =
(DESCRIPTION =
(ENABLE = BROKEN)
(LOAD_BALANCE = off)
(FAILOVER = on)
(ADDRESS = (PROTOCOL = TCP)(HOST = oradb2-vip)(PORT = 1523))
(CONNECT_DATA =
(SERVICE_NAME = TESTA)
(INSTANCE_NAME = TESTA2)
(FAILOVER_MODE =
(BACKUP = TESTA1)
(TYPE = SELECT)
(METHOD = PRECONNECT)
(RETRIES = 120)
(DELAY = 5))))
Load Balancing
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One service
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Oracle Net determines which node you use
Tries to balance the load
Only active nodes are used
Balance is somewhat random
In the event of a failure
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Transaction is lost
Connection is lost
Load Balancing
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TESTA =
(DESCRIPTION =
(ADDRESS_LIST =
(LOAD_BALANCE = on)
(FAILOVER = off)
(ADDRESS = (PROTOCOL = TCP)(HOST = oradb1-vip)(PORT =
1523))
(ADDRESS = (PROTOCOL = TCP)(HOST = oradb2-vip)(PORT =
1523))
)
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = TESTA)
)
)
Transparent Application
Failover
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One service
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Multiple sessions are created
Only active nodes are used
In the event of a failure
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available node is used
No loss of connection
Transaction is lost
Query is restarted
Transparent Application
Failover
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TESTA =
(DESCRIPTION =
(ENABLE = BROKEN)
(ADDRESS_LIST =
(LOAD_BALANCE = on)
(FAILOVER = on)
(ADDRESS = (PROTOCOL = TCP)(HOST = oradb1-vip)(PORT = 1523))
(ADDRESS = (PROTOCOL = TCP)(HOST = oradb2-vip)(PORT = 1523))
)
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = TESTA)
(FAILOVER_MODE =
(TYPE = SELECT)
(METHOD = BASIC)
(RETRIES = 120)
(DELAY = 5)
)
)
)
Characteristics of TAF
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TAF protects:
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Client/server connection
User session state
OCI programs
Java thick drivers (OCI drivers)
Sql*plus
Active cursors (select statements) that have begun to return
results
Not failed over:
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Active update transactions
PL/SQL procedure states
PL/SQL server-side package variables
alter session statements
Server side program variables
Uncommitted transactions
Network Timeouts and TAF
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When a “planned” instance shutdown occurs, failover
occurs quickly
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When an “unplanned” instance failure occurs, failover
timing is sensitive to network timeout parameters
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Shutdown instance with srvctl or OEM
Failover takes a few seconds
Failover cannot occur until the network connection is released
By default, it may take up to eight minutes for the network
connection to be released and for failover to occur
Server-side and client-side operating system level
TCP/IP timeout parameters may be shortened to speed
up failover
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Failover can occur as quickly as one minute
Can increase risk of disrupted network connections and
unnecessary failover events
Example Windows TCP/IP
Timeout Parameters for TAF
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The following steps may be performed on
Windows database servers, mid-tier servers,
and clients to speed up failover
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Open the registry hive under
HKEY_LOCAL_MACHINE : SYSTEM
CurrentControlSet : Services : Tcpip : Parameters
Add KeepAliveTime : REG_DWORD to the registry
Note: The correct case is required for KeepAlive
Set the value to a reasonable timeout. Eg: (120000 =
2 minutes, 60000 = 1 minute)
JDBC Connections and TAF
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The Oracle JDBC thick driver supports TAF
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tnsnames,ora file must be defined on the server-side
JDBC Data Source file must be defined on the clientside (or mid-tier)
TAF failover and load balancing are supported
The Oracle JDBC thin driver does not fully
support TAF
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tnsnames,ora file must be defined on the server-side
JDBC Data Source file must be defined on the clientside (or mid-tier)
Load balancing is supported, but not TAF failover
JDBC Thick Driver Example
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<data-source
class="com.evermind.sql.DriverManagerDataSource"
name="OracleDS"
location="jdbc/OracleCoreDS"
xa-location="jdbc/xa/OracleXADS"
ejb-location="jdbc/OracleDS"
connection-driver="oracle.jdbc.driver.OracleDriver"
username="scott"
password="tiger"
url="jdbc:oracle:oci8:@(description=(load_balance=on)(failover=on)
(address=(protocol=tcp)(host=db-node1)(port=1521))
(address=(protocol=tcp)(host=db-node2)(port=1521))
(address=(protocol=tcp)(host=db-node3)(port=1521))
(address=(protocol=tcp)(host=db-node4)(port=1521))
(connect_data=
(service_name=sales.us.oracle.com)
(failover_mode=(type=select)(method=basic)(retries=20)(delay=15))))"
rac-enabled="true"
inactivity-timeout="300"
connection-retry-interval="2"
max-connect-attempts="60"
max-connections="60"
min-connections="12"
/>
JDBC Thin Driver Example
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<data-source
class="com.evermind.sql.DriverManagerDataSource"
name="OracleDS"
location="jdbc/OracleCoreDS"
xa-location="jdbc/xa/OracleXADS"
ejb-location="jdbc/OracleDS"
connection-driver="oracle.jdbc.driver.OracleDriver"
username="scott"
password="tiger"
url="jdbc:oracle:thin:@(DESCRIPTION=
(LOAD_BALANCE=on)
(ADDRESS=(PROTOCOL=TCP) (HOST=host1) (PORT=1521))
(ADDRESS=(PROTOCOL=TCP) (HOST=host2) (PORT=1521))
(CONNECT_DATA=(SERVICE_NAME=service_name)))"
inactivity-timeout="300"
connection-retry-interval="2"
max-connect-attempts="60"
max-connections="60"
min-connections="12"
/>
Fast Application Notification
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ONS and Fast Application Notification
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The Oracle Notification Service provides a
framework for passing event messages
about failover between nodes
ONS may notify both RAC nodes and client
or mid-tier nodes
Fast Application Notification provides the
basis for Fast Connection Failover
Fast Connection Failover
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Fast Connection Failover provides a way to
control failover response
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Effective for Oracle 10g Application Server JDBC
connections
More mid-tier applications may be supported in the
future
Works with JDBC Thick and JDBC Thin drivers
Provides an alternative to TAF
Avoids network timeout sensitivity
Fast and efficient
Pre-requisites for Fast
Connection Failover
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The JDBC Implicit Connection Cache is
enabled.
The application uses service names to connect
to the database, not service ids.
The database should be at least release
10.1.0.2 (10.1.0.3 is preferred).
ONS is configured and running on the node
where JDBC is running.
The JVM in which the JDBC instance is running
must have oracle.ons.oraclehome set to point
to the ORACLE_HOME where the ONS files
were installed.
Setting Up the Implicit
Connection Cache for FCF
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The following JDBC Data Source file sets up the Implicit Connection Cache for FCF
on the Application Tier:
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OracleDataSource ods = new OracleDataSource()
...
ods.setUser(“Scott”);
ods.setPassword(“tiger”);
ods.setConnectionCachingEnabled(True);
ods.setFastConnectionFailoverEnabled(True);
ods.setConnectionCacheName(“MyCache”);
ods.setConnectionCacheProperties(cp);
ods.setURL("jdbc:oracle:thin:@(DESCRIPTION=
(LOAD_BALANCE=on)
(ADDRESS=(PROTOCOL=TCP)(HOST=VIP1)(PORT=1521))
(ADDRESS=(PROTOCOL=TCP)(HOST=VIP2)(PORT=1521))
(CONNECT_DATA=(SERVICE_NAME=service_name)))");
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ONS on the Applications Tier
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The Oracle Notification Service must be
installed and running on the Applications
Tier nodes
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The ONS client is available with the 10.1.0.3
client CD
For the 10.1.0.2 ONS client, contact Oracle
Support
Run “onsctl ping” on each application
node to determine that ONS is running
ONS on the Applications Tier
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Edit the file %ORACLE_HOME%\opmn\conf\ons.config
on each mid-tier node:
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localport=6100 # This is the port ONS is writing to on this node
remoteport=6200 # This is the port ONS is listening on this
node
loglevel=3
# This is the list of hosts and ports ONS is posting to.
# Include RAC and client nodes.
nodes=RAC1.mycompany.com:6200,RAC2.mycompany.com:6
200,
RAC3.mycompany.com:6200,APPS1.mycompany.com:6200,
APPS2.mycompany.com:6200
ONS on the Applications Tier
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When starting the application:
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Specify the system property –
Doracle.ons.iraclehome=<location of ons on
client>
Include the ons.jar file in the application
CLASSPATH
Modifying Server-Side ONS for
FCF
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Use the %ORA_CRS_HOME%\bin\racgons
command to modify the server-side ONS
configuration to be aware of the mid-tier nodes:
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racgons add_config APPS1.mycompany.com:6200
APPS2.mycompany.com:6200
This adds the host and port names to the OCR
Differences between FCF and
TAF
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Application-Level Connection Retries.
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Fast Connection Failover supports
application-level connection retries. This
gives the application control of responding to
connection failovers.
TAF supports connection retries only at the
OCI/Net layer.
Differences between FCF and
TAF
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Integration with the Connection Cache
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Fast Connection Failover is well-integrated
with the Implicit Connection Cache, which
allows the connection cache manager to
manage the cache for HA.
Failed connections are automatically
invalidated in the cache.
TAF works at the network level on a perconnection basis, which means that the
connection cache cannot be notified of
failures.
Differences between FCF and
TAF
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Event-Based
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Fast Connection Failover is based on the
RAC event mechanism. This means that Fast
Connection Failover is efficient and detects
failures quickly for both active and inactive
connections.
TAF is based on the network call mechanism.
Differences between FCF and
TAF
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Load-Balancing Support
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Fast Connection Failover supports UP event
load balancing of connections and runtime
work request distribution across active RAC
instances.
Review
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What are the two key configuration files for
Oracle Net?
What key phrase in the tnsnames.ora file
influences load balance behaviour?
What key phrase in the tnsnames.ora file
influences failover behaviour?
Which Oracle Net configurations allow users
to maintain connections through a failover
event?
Which JDBC drivers are supported under TAF
and FCF?
What is the name of the utility to add mid-tier
nodes to the server-side ONS configuration?
Summary
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Listener process
Configuration files
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Failover
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listener.ora
tnsnames.ora
Basic
Preconnect
Load Balancing
TAF
JDBC Thick and Thin drivers and TAF
Setting up Fast Connection Failover