Understanding Oracle RAC 11g Release 2 Internals

1/20/2012

1 Copyright © 2011, Oracle and/or its affiliates. All rights reserved.

Understanding Oracle RAC Internals
Markus Michalewicz (Markus.Michalewicz@oracle.com)
Senior Principal Product Manager Oracle RAC and Oracle RAC One Node

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1/20/2012

Safe Harbor Statement

The following is intended to outline our general product direction. It is intended for
information purposes only, and may not be incorporated into any contract. It is not a
commitment to deliver any material, code, or functionality, and should not be relied upon
in making purchasing decisions. The development, release, and timing of any features
or functionality described for Oracle’s products remains at the sole discretion of Oracle.


Agenda
• The Oracle RAC Architecture
• VIPs and Networks
• Listeners and SCAN
– and Services
• Client Connectivity
• Node Membership
• The Interconnect
• Installation and Upgrade


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The Oracle RAC Architecture
Typical hardware architecture
Network

Public Lan Client
Node 1 Node 2 Node N-1 Node N

Interconnect
with switch

SAN switch

Shared Storage


Typical software deployment 11g Release 2

Oracle Real Application Clusters (RAC)
Oracle Grid Infrastructure
OS OS OS OS

Shared Storage


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Typical software deployment 11g Release 2

Oracle Real Application Clusters (RAC)
Oracle Automatic Storage Management (ASM)
Oracle Clusterware
OS OS OS OS

Oracle ASM managed
Shared Storage


Oracle RAC 11g Release 2 per node layer
• Cloud File System
(aka ASM Cluster File
File System - ACFS)
DB Instance • For all other files
Oracle RAC
• 11.2.0.3: For Backup Sets
ASM Instance
Oracle Grid Infrastructure • Oracle Clusterware files
HA Framework
OS OS • Voting Files (disks)
Node
Membership • Cluster Registry (OCR)
OS • Database Files
• Redo / Archive Logs
Oracle ASM managed • Control Files
Shared Storage • etc.


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Oracle Grid Infrastructure 11g Release 2 process overview

ASM Instance
HA Framework
OS OS
Node
Membership
• My Oracle Support (MOS) OS
• Note 1053147.1 - 11gR2 Clusterware
and Grid Home - What You Need to Know
• Note 1050908.1 - How to Troubleshoot
Grid Infrastructure Startup Issues


Local and Cluster Resources (11.2.0.2 list)

LISTENER_SCAN1 LISTENER_SCAN2 LISTENER_SCAN3 ora.oc4j If database is deployed:
ora.SCAN1.VIP ora.SCAN2.VIP ora.SCAN3.VIP ora.cvu
• ora.Dbname.db
ora.node1.vip ora.node2.vip ora.node3.vip ora.node4.vip
• ora.Dbname.Srvcname.svc
ora.asm ora.asm ora.asm ora.asm
ora.dgname.dg ora.dgname.dg ora.dgname.dg ora.dgname.dg
Command to list:
ora.listener.lsnr ora.listener.lsnr ora.listener.lsnr ora.listener.lsnr
• crsctl stat res -t
ora.ons ora.ons ora.ons ora.ons
ora.gsd ora.gsd ora.gsd ora.gsd
ora.net1.network ora.net1.network ora.net1.network ora.net1.network
ora.registry.acfs ora.registry.acfs ora.registry.acfs ora.registry.acfs

OS OS OS OS


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VIPs and Networks


VIPs and Networks
Oracle VIPs
• SCAN and node VIPs are cluster resources
• SCAN VIPs can float in the cluster
• Node VIPs per default run on specific nodes rac1 rac2
LISTENER_SCAN1 LISTENER_SCAN2
ora.SCAN1.VIP ora.SCAN2.VIP
ora.rac1.vip ora.rac2.vip
• All VIPs on the public network (SCAN, node,
user or application VIPs) depend on the Oracle … …
network resource. ora.listener.lsnr ora.listener.lsnr
… …
• The network resource monitors
ora.net1.network ora.net1.network
the public network interface(s).
• IOCTL based checks vs. default gateway ping
OS OS
• Default gateway checks as backup
• racgvip for backward compatibility only


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VIPs and Networks
Node VIP Details
[GRID]> crsctl status res ora.rac1.vip -p
NAME=ora.rac1.vip
TYPE=ora.cluster_vip_net1.type
...
1 AGENT_FILENAME=%CRS_HOME%/bin/orarootagent%CRS_EXE_SUFFIX%
... rac1 rac2
CHECK_INTERVAL=1 … …
2 CHECK_TIMEOUT=30 … …
... ora.rac1.vip ora.rac2.vip
START_DEPENDENCIES=hard(ora.net1.network)
3 pullup(ora.net1.network) … …
... ora.listener.lsnr ora.listener.lsnr
STOP_DEPENDENCIES=hard(ora.net1.network) … …
... ora.net1.network ora.net1.network
USR_ORA_VIP=rac1-vip
VERSION=11.2.0.2.0 Oracle Grid Infrastructure
OS OS


VIPs and Networks
The network resource
• The Oracle network resource monitors the
public network interface(s) (e.g. eth0).
• The default is network number 1 (net1)
• There is one network resource per subnet: rac1 rac2
… …
[GRID]> srvctl config network … …
Network exists: ora.rac1.vip ora.rac2.vip
1/192.168.0.0/255.255.255.0/eth0, type static
… …
ora.listener.lsnr ora.listener.lsnr
• New in 11.2.0.2: … …
• Direct management of the network resource ora.net1.network ora.net1.network

• srvctl verb network Oracle Grid Infrastructure
• Network type support (static, dhcp, mixed) OS OS


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VIPs and Networks
How to enable multiple networks in the cluster?
1 [GRID]> srvctl add network –h
Adds a network configuration to the Oracle Clusterware.
Usage: srvctl add network
-k <net_num> network number
(default number is 1)
-S <subnet>/<netmask>/[if1[|if2...]]
NET address spec for network
-w <network_type> The network type
(static, dhcp, mixed) … …
-h Print usage
-v Verbose output … …

• For example:
srvctl add network -k 2 -S 10.1.1.0/255.255.255.0 OS OS


VIPs and Networks
How to enable multiple networks in the cluster?
2 [GRID]> srvctl add vip -h
Adds a VIP to the Oracle Clusterware.
Usage: srvctl add vip
-n <node_name> Node name
-A <vip_name|ip>/<netmask>/[if1[|if2...]] ora.rac1.vip ora.rac2.vip
VIP address spec for node applications ora.rac1-vip2.vip ora.rac2-vip2.vip
-k <net_num> network number
(default number is 1) … …
-h Print usage ora.net1.network ora.net1.network
-v Verbose output
… …

• For example:
srvctl add vip -n rac1 -k 2 -A rac1-vip2/255.255.255.0 OS OS
srvctl add vip -n rac2 -k 2 -A rac2-vip2/255.255.255.0


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VIPs and Networks
Application / user and node VIPs
1 [GRID]> crsctl stat res ora.rac1-vip2.vip -p
NAME=ora.rac1-vip2.vip
TYPE=ora.cluster_vip_net2.type
...
HOSTING_MEMBERS=rac1 This is a node vip! ora.rac1.vip ora.rac2.vip
ora.rac1-vip2.vip ora.rac2-vip2.vip
...
START_DEPENDENCIES=hard(ora.net2.network)
pullup(ora.net2.network) … …
...
STOP_DEPENDENCIES=hard(ora.net2.network)
… …
...
USR_ORA_VIP=rac1-vip2
OS OS
VERSION=11.2.0.2.0


VIPs and Networks
2 [GRID]> appvipcfg create
-network=1
-ip 192.168.0.66
-vipname=myVIP
-user=root

This is an application vip! ora.rac1.vip ora.rac2.vip
[GRID]> appvipcfg create ora.rac1-vip2.vip ora.rac2-vip2.vip
-network=2
-ip 10.1.1.88 myVIP myNewVIP
-vipname=myNewVIP … …
-user=root
… …
OS OS


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VIPs and Networks
3 [GRID]> crsctl stat res myVIP -p
NAME=myVIP
TYPE=app.appvip_net1.type
...
HOSTING_MEMBERS=rac1 This is an application vip! ora.rac1.vip ora.rac2.vip
ora.rac1-vip2.vip ora.rac2-vip2.vip
...
RESTART_ATTEMPTS=0 myVIP myNewVIP
... … …
USR_ORA_VIP=192.168.0.66
VERSION=11.2.0.2.0 … …
• You can modify it as needed! OS OS


Listeners and SCAN


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Listeners
Listeners and dependencies

• In Oracle RAC 11g Release 2 there have been
three major changes regarding listeners: rac1 rac2
LISTENER_SCAN1 LISTENER_SCAN2
1. Listeners per default now run from the ora.SCAN1.VIP ora.SCAN2.VIP
Oracle Grid Infrastructure (GRID) home ora.rac1.vip ora.rac2.vip

2. Listeners are managed by an Oracle agent … …
ora.listener.lsnr ora.listener.lsnr
3. SCAN Listeners were introduced
… …
• A listener depends on a VIP Oracle Grid Infrastructure
• A listener depends indirectly on a network OS OS


Listeners
The default LISTENER
[GRID]> srvctl config listener
Name: LISTENER
Network: 1, Owner: oracle  Grid Software Owner
Home: <CRS home>
rac1 rac2
End points: TCP:1521

… …
ora.LISTENER.lsnr ora.LISTENER.lsnr
… …

OS OS


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Listeners
The default LISTENER FAQ

• Can you define another port? - YES

rac1 rac2
• Can you define another owner? – YES

• Can you define another home? – YES, if really needed. … …
… …

• Can I add another listener on another port? - YES ora.net1.network ora.net1.network

OS OS


Can you define another port? - YES
1 [GRID]> srvctl modify listener -l LISTENER -p TCP:1545

Name: LISTENER
rac1 rac2
Network: 1, Owner: oracle
Home: <CRS home>
… …
• Check: <CRS HOME>/network/admin/endpoints_listener.ora before: … …
LISTENER_RAC1=(DESCRIPTION=(ADDRESS_LIST= ora.net1.network ora.net1.network
(ADDRESS=(PROTOCOL=TCP)(HOST=rac1-vip)
(PORT=1521))(ADDRESS=(PROTOCOL=TCP) Oracle Grid Infrastructure
(HOST=192.168.0.51)(PORT=1521)(IP=FIRST)))) OS OS
# line added by Agent


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Can you define another port? - YES
2 [GRID]> srvctl modify listener -l LISTENER -p TCP:1545

Name: LISTENER
rac1 rac2
Home: <CRS home>
… …
• Check: <CRS HOME>/network/admin/endpoints_listener.ora after restart: … …
LISTENER_RAC1=(DESCRIPTION=(ADDRESS_LIST= ora.net1.network ora.net1.network
(ADDRESS=(PROTOCOL=TCP)(HOST=rac1-vip)
(PORT=1545))(ADDRESS=(PROTOCOL=TCP) Oracle Grid Infrastructure
(HOST=192.168.0.51)(PORT=1545)(IP=FIRST)))) OS OS
# line added by Agent


Can you define another owner? - YES
[GRID]> srvctl modify listener -l LISTENER -u root
You need to be root…
Name: LISTENER
rac1 rac2
Network: 1, Owner: root  For demonstration
purposes only…
Home: <CRS home>
End points: TCP:1545 … …
… …

OS OS


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Can you define another home? - YES
[GRID]> srvctl modify listener -l LISTENER
-o /u01/app/oracle/product/11.2.0/dbhome_1

Name: LISTENER
rac1 rac2
Home: /u01/app/oracle/product/11.2.0/dbhome_1
… …
… …
• This may not be required.
• Instead, create a new listener from a separate home, if needed
and use the SRVCTL command as shown, but try using the GI home. OS OS


Listeners
Can I add another listener on another port? - YES
Name: LISTENER
Home: <CRS home>
rac1 rac2
Name: LISTENER2011
… …
Home: <CRS home>
End points: TCP:2011 ora.LISTENERK2.lsnr ora.LISTENERK2.lsnr

• MOS Note 220970.1 - RAC: Frequently Asked Questions
• How to use SCAN and node listeners with different ports?
OS OS
• Add additional node listeners to the system using different ports


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Listeners
Can I add another listener on another network? - YES
[GRID]> srvctl add listener -l ListenerK2 -p 1544 -k 2
Name: LISTENER
rac1 rac2
Home: <CRS home>
Name: LISTENERK2 ora.LISTENER.lsnr ora.LISTENER.lsnr
Ora.LISTENERK2.lsnr ora.LISTENERK2.lsnr
Home: <CRS home> ora.net2.network ora.net2.network

• MOS Note 1063571.1 - How to Configure A Second
OS OS
Listener on a Separate Network in 11.2 Grid Infrastructure


Listeners
Remember – it’s just another listener …
1 [GRID]> srvctl config listener
Name: JUSTALISTENER
Network: 1, Owner: root
Home: <CRS home>
rac1 rac2
End points: TCP:1522 LISTENER_SCAN1 LISTENER_SCAN2
... ora.SCAN1.VIP ora.SCAN2.VIP
ora.rac1.vip ora.rac2.vip
[GRID]> vi /u01/app/11.2.0/grid/network/admin/listener.ora
… …
JUSTALISTENER=(DESCRIPTION=(ADDRESS_LIST=
(ADDRESS=(PROTOCOL=IPC)(KEY=JUSTALISTENER))))
# line added by Agent … …
[GRID]> vi /u01/app/11.2.0/grid/network/admin/endpoints_listener.ora
JUSTALISTENER_RAC1=(DESCRIPTION=(ADDRESS_LIST= Oracle Grid Infrastructure
(ADDRESS=(PROTOCOL=TCP)(HOST=rac1-vip)(PORT=1522))
(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.51)(PORT=1522)(IP=FIRST))))
OS OS


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Listeners
Remember – it’s just another listener …
2 [GRID]> vi /u01/app/11.2.0/grid/network/admin/listener.ora
(ADDRESS=(PROTOCOL=IPC)(RATE_LIMIT=10)  For demonstration purposes only…
(KEY=JUSTALISTENER)))) # line added by Agent
... rac1 rac2
[GRID]> srvctl stop listener -l JustAListener LISTENER_SCAN1 LISTENER_SCAN2
ora.SCAN1.VIP ora.SCAN2.VIP
[GRID]> srvctl start listener -l JustAListener ora.rac1.vip ora.rac2.vip
[GRID]> vi /u01/app/11.2.0/grid/network/admin/listener.ora … …
... ora.LISTENER.lsnr ora.LISTENER.lsnr
[GRID]> vi /u01/app/11.2.0/grid/network/admin/listener.ora … …
(ADDRESS=(PROTOCOL=IPC)(RATE_LIMIT=10) Oracle Grid Infrastructure
(KEY=JUSTALISTENER)))) # line added by Agent
OS OS


SCAN
The basics and overview
• In Oracle RAC 11g Release 2
SCAN Listeners were introduced SCAN
• There is one SCAN setup per cluster

• Read about SCAN: rac1 rac2 rac3
LISTENER_SCAN1 LISTENER_SCAN2 LISTENER_SCAN3
• http://www.oracle.com/technetwork/database/
ora.SCAN1.VIP ora.SCAN2.VIP ora.SCAN3.VIP
clustering/overview/scan-129069.pdf
… … …
• MOS Note 887522.1 –
… … …
11gR2 Grid Infrastructure Single Client
Access Name (SCAN) Explained ora.LISTENER.lsnr ora.LISTENER.lsnr ora.LISTENER.lsnr
… … …
ora.net1.network ora.net1.network ora.net1.network
• SCAN consists of a bundle containing:
1. SCAN IP
OS OS OS
2. Associated (dependency) SCAN Listener


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SCAN
The SCAN bundle
1 • 3 SCANs are the default for HA and LB
• Regardless of number of nodes SCAN
• You can define less or more, if really needed.
• SCAN listener resources run with rac1 rac2 rac3
an active dispersion dependency LISTENER_SCAN1 LISTENER_SCAN2 LISTENER_SCAN3

• If you use more nodes in the cluster than ora.SCAN1.VIP ora.SCAN2.VIP ora.SCAN3.VIP
… … …
SCAN listeners are defined, no node should
run more than one SCAN bundle at a time … … …
ora.LISTENER.lsnr ora.LISTENER.lsnr ora.LISTENER.lsnr
• If you use less nodes in the cluster than … … …
SCAN listeners are defined, there will be ora.net1.network ora.net1.network ora.net1.network
nodes running more than one SCAN bundle
at a time. Oracle Grid Infrastructure
• SCAN VIP moves with the listener, if possible. OS OS OS


SCAN
The SCAN bundle
2 [GRID]> srvctl config scan
SCAN name: cluster1, Network: 1/192.168.0.0/255.255.255.0/eth0
SCAN VIP name: scan1, IP: /cluster1.us.oracle.com/192.168.0.41 SCAN
rac1 rac2
[GRID]> srvctl modify scan LISTENER_SCAN1 …
Modifies the SCAN name. ora.SCAN1.VIP …
… …
Usage: srvctl modify scan
… …
-n <scan_name> Domain name qualified SCAN name
-h Print usage … …

• http://www.oracle.com/technetwork/database/ Oracle Grid Infrastructure
clustering/overview/scan-129069.pdf page 2 OS OS


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SCAN
The SCAN bundle
3 [GRID]> srvctl add scan -h
Adds a SCAN VIP to the Oracle Clusterware.
Usage: srvctl add scan -n <scan_name> SCAN
-n <scan_name> Domain name qualified SCAN name
rac1 rac2
-k <net_num> network number (default number is 1) LISTENER_SCAN1 …
-S <subnet>/<netmask>/[if1[|if2...]] ora.SCAN1.VIP …
NET address spec for network … …

-h Print usage … …
… …
• Note: SCAN can only operate on one network / in one subnet. ora.net1.network ora.net1.network

OS OS


SCAN
The SCAN FAQ
1 • From MOS Note 220970.1 –
RAC: Frequently Asked Questions
SCAN
• With Oracle RAC 11g Release 2 using SCAN is the default.
rac1 rac2
• As with other listeners, there is no direct communication LISTENER_SCAN1 …
between the node (listeners) and the SCAN listeners. ora.SCAN1.VIP …
… …
• Listeners are only aware of the instances and services served,
since the instances (PMON) register themselves and the services … …
they host with the listeners. ora.LISTENER.lsnr ora.LISTENER.lsnr
… …
• The instances use the LOCAL and REMOTE Listener
parameters to know with which listeners to register.
• Listeners used for a client connection to Oracle RAC should be Oracle Grid Infrastructure
managed by Oracle Clusterware and should be listening on an OS OS
Oracle managed VIP.


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SCAN
The SCAN FAQ
2 • Can you define another port? - YES
• See MOS Note 220970.1 –
SCAN
rac1 rac2
• Use srvctl modify scan_listener –p <newPort>
LISTENER_SCAN1 …
• Can you define another owner? – NO ora.SCAN1.VIP …
… …
• Can you define another home? – NO
… …
• Can you have more than one node listener with SCAN? – YES … …
• Can the SCAN and the node listener ports differ? - YES ora.net1.network ora.net1.network

• See also MOS Note 972500.1 – How to Oracle Grid Infrastructure
Modify SCAN Setting or SCAN Listener Port after Installation OS OS


Listeners and Instance Registration
Listener changes may require instance changes
• See MOS Note 220970.1 –
SCAN

• Whenever you change an instance parameter configuration rac1 rac2
a change to the LOCAL_LISTENER or REMOTE_LISTENER
DB Instance DB Instance
per database (instance) may be required.
LISTENER_SCAN1 …
• Note that using server-side TNSANMES aliases to ora.SCAN1.VIP …
resolve the listener configuration is not recommended. … …

• The use of the TNSNAMES connector string is the default: ora.LISTENER.lsnr ora.LISTENER.lsnr
… …
local_listener = ‘(DESCRIPTION= (ADDRESS_LIST=
(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.61)(PORT=2011))
))' OS OS


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EXAMPLE
1 • Taken from MOS Note 220970.1 – RAC: FAQ
• Add additional node listeners to the system using different ports SCAN

• srvctl add listener -l LISTENER2011 -p 2011 rac1 rac2
• srvctl start listener -l LISTENER2011
• srvctl status listener -l LISTENER2011
LISTENER_SCAN1 …
• lsnrctl status LISTENER2011 ora.SCAN1.VIP …
… …
[GRID]> srvctl config listener ora.LISTENER.lsnr ora.LISTENER.lsnr
Name: LISTENER2011 … …

Network: 1, Owner: oracle Oracle Grid Infrastructure
Home: <CRS home> OS OS


EXAMPLE
rac1 rac2
• New node listener does not serve any database instance
• You must alter the LOCAL_LISTENER parameters
LISTENER_SCAN1 …
for each instance accordingly:
ora.SCAN1.VIP …

alter system set local_listener =‘ … …

(DESCRIPTION= (ADDRESS_LIST= ora.LISTENER.lsnr ora.LISTENER.lsnr
(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.61)(PORT=2011)))) …
…
' scope=BOTH SID='OCRL1';
alter system register; Oracle Grid Infrastructure
OS OS


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EXAMPLE
rac1 rac2
• Note: Use spaces between the various segments of the command
• Reason: the database agent in Oracle Clusterware currently
LISTENER_SCAN1 …
determines whether the local_listener or remote_listener have
ora.SCAN1.VIP …
been manually set by a string comparison operation. … …
• If the string looks unaltered it will reset these parameters ora.LISTENER.lsnr ora.LISTENER.lsnr
with the default values that it determines on instance startup. … …
• Slight modifications are therefore required. ER 11772838 Oracle Grid Infrastructure
has been filed to allow for a more convenient mechanism.
OS OS


Using listeners in different subnets / networks
• SCAN can only operate in one network / subnet
rac1 rac2

• If listeners in different subnets are used,
LISTENER_SCAN1 …
• use LISTENER_NETWORKS: ora.SCAN1.VIP …
http://download.oracle.com/docs/cd/E11882_01 … …
… …
/server.112/e17110/initparams115.htm#REFRN10313
• Note: Listeners specified by the LISTENER_NETWORKS Ora.LISTENERK2.lsnr ora.LISTENERK2.lsnr
parameter should not be used in the LOCAL_LISTENER and
REMOTE_LISTENER parameters. Otherwise, cross registration
will happen and connections will be redirected cross networks. ora.net2.network ora.net2.network
… …

• For more information, see also
MOS Note 1063571.1 – How to Configure A Second OS OS
Listener on a Separate Network in 11.2 Grid Infrastructure


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Listeners, SCAN and Services


Listeners and Service Registration
A summary
• Services depend on a database
• Per default, the database instance will register
all services it hosts with all listeners it registers with.
SCAN
rac1 rac2
• Services operate within the following boundaries:
• Network (indirectly via dependency)
ora.Dbname.db ora.Dbname.db
• Server Pools (in policy-managed database environments) ora.Dbname.Srvcname.svc ora.Dbname.Srvcname.svc

… …

• Currently there is no support for service failover
… …
• Between Server Pools
• Between networks
OS OS


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Services and Dependencies
Dependency on DB and Server Pool
[GRID]> srvctl config service -d ORCL -s MyService
1
Service name: MyService
Service is enabled
SCAN
Server pool: ORCL
rac1 rac2
Cardinality: 1
Disconnect: false DB Instance DB Instance
Service role: PRIMARY ora.ORCL.db ora.ORCL.db
ora.ORCL.MyService.svc ora.Dbname.Srvcname.svc
Management policy: AUTOMATIC … …
...
Preferred instances: ORCL_1 … …
Available instances:
OS OS


Services and Dependencies
Start / Stop dependencies
[GRID]> crsctl stat res ora.orcl.myservice.svc -p
2
...
DEFAULT_TEMPLATE=PROPERTY(RESOURCE_CLASS=service)
PROPERTY(SERVICE_NAME=%GEN_SERVICE_NAME%) SCAN
PROPERTY(DB_UNIQUE_NAME=CONCAT(PARSE(%NAME%, ., rac1 rac2
2), STAT(ora.orcl.db, USR_ORA_DOMAIN), .))
ELEMENT(INSTANCE_NAME=STAT(ora.orcl.db, DB Instance DB Instance
GEN_USR_ORA_INST_NAME))
ora.ORCL.db ora.Dbname.db
... ora.ORCL.MyService.svc ora.Dbname.Srvcname.svc

START_DEPENDENCIES=hard(ora.orcl.db,type:ora.cluster … …

_vip_net1.type) weak(type:ora.listener.type)
pullup(type:ora.cluster_vip_net1.type)
… …
pullup:always(ora.orcl.db)
dispersion(type:ora.service.type) Oracle Grid Infrastructure
STOP_DEPENDENCIES=hard(intermediate:ora.orcl.db,inte OS OS
rmediate:type:ora.cluster_vip_net1.type)
...

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Client Connectivity


Client Connectivity
Direct or indirect connect
• Connect Time Load Balancing (CTLB)
• Connect Time Connection Failover (CTCF)

• Runtime Connection Load Balancing (RTLB)
• Runtime Connection Failover (RTCF)

BATCH
Production
Email
SCAN

Connection
Pool


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Client Connectivity
Connect Time Connection Failover
jdbc:oracle:thin:@MySCAN:1521/Email

PMRAC =
(DESCRIPTION =
(FAILOVER=ON)
(ADDRESS = (PROTOCOL = TCP)(HOST = MySCAN)(PORT = 1521))
(CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = Email)))

BATCH
Production
Email

MySCAN
Connection
Pool


Client Connectivity
Runtime Time Connection Failover
PMRAC =
(DESCRIPTION =
(FAILOVER=ON)
(CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = Email)
...))

BATCH
Production
Email
MySCAN

Connection
Pool


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Client Connectivity
Runtime Time Connection Failover
PMRAC =
(DESCRIPTION =
(FAILOVER=ON)
(CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = Email)
(FAILOVER_MODE= (TYPE=select)(METHOD=basic)(RETRIES=180)(DELAY=5))))

BATCH
Production
Email

MySCAN

?
Connection
Pool


Client Connectivity
More information
• If problems occur, see:
• Note 975457.1 – How to Troubleshoot Connectivity Issues with 11gR2 SCAN Name
• For more advanced configurations, see:
• Note 1306927.1 – Using the TNS_ADMIN variable and changing the default port
number of all Listeners in an 11.2 RAC for an 11.2, 11.1, and 10.2 Database

??
BATCH
Production
Email
MySCAN

?
Connection
Pool


26

1/20/2012

Client Connectivity
Two ways to protect the client
1. Transparent Application Failover (TAF) 2. Fast Application Notification (FAN)
• Tries to make the client unaware of a failure • FAN wants to inform clients ASAP
• Provides means of CTCF and RTCF • Client can react to failure asap
• Allows for pure ‘selects’ (reads) to continue • Expects clients to re-connect on failure (FCF)
• Write transactions need to be re-issued • Sends messages about changes in the cluster
• The Application needs to be TAF aware

BATCH
Production
Email

MySCAN

?
Connection
Pool


Client Connectivity and Service Definition
Define settings on the server
• HA (and LB) settings [GRID]> srvctl config service
-d ORCL -s MyService
can be defined per service
Service name: MyService
• Clients connecting to the service will
...
adhere to the settings considering the
DTP transaction: false
client used.
AQ HA notifications: false
Failover type: NONE
BATCH Failover method: NONE
Production
Email
MySCAN

TAF failover retries: 0
TAF failover delay: 0
Connection Load Balancing Goal: LONG
Runtime Load Balancing Goal: NONE
TAF policy specification: BASIC


27

1/20/2012

Client Connectivity
Use a FAN aware connection pool
1• If a connection pool is used
• The clients (users) get a physical
connection to the connection pool
• The connection pool creates a physical
connection to the database
• It is a direct client to the database
• Internally the pool maintains logical connections

BATCH
Production Connection Pool
Email

MySCAN


Client Connectivity
Use a FAN aware connection pool
2• The connection pool
• Invalidates connections to one instance
• Re-establishes new logical connections
• May create new physical connections
• Prevent new clients to be misrouted

• The application needs to handle the
transaction failure that might have occurred.
BATCH
Production Connection Pool
Email
MySCAN


28

1/20/2012

Client Connectivity
The Load Balancing (LB) cases

• On the Client Side
• On the Server Side
BATCH
Production

MySCAN
Email

Connection
Pool


Client Connectivity
Connect Time Load Balancing (CTLB) – on the client side
PMRAC =
(DESCRIPTION =
(FAILOVER=ON)(LOAD_BALANCE=ON)
(CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = Email)))

BATCH
Production
Email
MySCAN

Connection
Pool


29

1/20/2012

Client Connectivity
Connect Time Load Balancing (CTLB) – on the server side
• Traditionally, PMON dynamically registers the services to the specified listeners with:
• Service names for each running instance of the database and instance names for the DB
• The listener is updated with the load information for every instance and node as follows:
• 1-Minute OS Node Load Average all 30 secs.
• Number of Connections to Each Instance
• Number of Connections to Each Dispatcher

BATCH
Production
Email

MySCAN
Connection
Pool

?

Client Connectivity
Use FAN for the Load Balancing cases
• Connect Time Connection Failover (CTCF)

• Runtime Connection Load Balancing (RTLB) RAC
Database
• Runtime Connection Failover (RTCF) 30% connections

I’m busy
Instance1
10% connections

I’m very busy

I’m idle Instance2

60% connections
Instance3


30

1/20/2012

Client Connectivity
Use FAN for the Load Balancing cases
• Also via AQ (Advanced Queuing) based notifications
• Background is always the Load Balancing Advisory RAC
Database

30% connections

I’m busy
Instance1
10% connections

MySCAN
• For more information, see: I’m very busy

• Oracle® Real Application I’m idle Instance2
Clusters Administration and
Deployment Guide 11g Release 2:
5 Introduction to Automatic Workload Management 60% connections
Instance3


Node Membership


31

1/20/2012

Oracle Clusterware Architecture
Node Membership Processes and Basics
Public Lan Public Lan

Main processes involved: Private Lan /
Interconnect
• CSSD (ora.cssd)
Oracle Clusterware
• CSSDMONITOR
• was: oprocd
CSSD CSSD CSSD
• now: ora.cssdmonitor

SAN SAN
Network Network
Voting
Disk


What does CSSD do?
• Monitors nodes using 2 communication channels:
– Private Interconnect  Network Heartbeat
– Voting Disk based communication  Disk Heartbeat

• Evicts (forcibly removes nodes from a
cluster) nodes dependent on heartbeat Oracle Clusterware
feedback (failures)

CSSD “Ping” CSSD

“Ping”


32

1/20/2012

Interconnect basics – network heartbeat
• Each node in the cluster is “pinged” every second

• Nodes must respond in css_misscount time (defaults to 30 secs.)
– Reducing the css_misscount time is generally not supported

• Network heartbeat failures “Ping”
will lead to node evictions
– CSSD-log:
[date / time] [CSSD][1111902528]
clssnmPollingThread: node mynodename CSSD CSSD
(5) at 75% heartbeat fatal, removal
in 6.770 seconds


Voting Disk basics – disk heartbeat
1 • Each node in the cluster “pings” (r/w) the Voting Disk(s) every second

• Nodes must receive a response in (long / short) diskTimeout time
– IF I/O errors indicate clear accessibility problems  timeout is irrelevant

• Disk heartbeat failures
will lead to node evictions
– CSSD-log: …
[CSSD] [1115699552] >TRACE:
clssnmReadDskHeartbeat: CSSD CSSD
node(2) is down. rcfg(1) wrtcnt(1)
LATS(63436584) Disk lastSeqNo(1)

“Ping”


33

1/20/2012

Voting Disk basics – Structure
2 • Voting Disks contain dynamic and static data:
– Dynamic data: disk heartbeat logging
– Static data: information about the nodes in the cluster

• With 11.2.0.1 Voting Disks got an “identity”:
– E.g. Voting Disk serial number: [GRID]> crsctl query css votedisk
1. 2 1212f9d6e85c4ff7bf80cc9e3f533cc1 (/dev/sdd5) [DATA]

Node information Disk Heartbeat Logging

• Voting Disks must therefore not be copied using “dd” or “cp” anymore


Voting Disk basics – Simple Majority rule
3 • Oracle supports redundant Voting Disks for disk failure protection
• “Simple Majority Rule” applies:
– Each node must “see” the simple majority of configured Voting Disks
at all times in order not to be evicted (to remain in the cluster)

 trunc(n/2+1) with n=number of voting disks
configured and n>=1

CSSD CSSD

“Ping”


34

1/20/2012

Simple Majority rule – in extended clusters

• http://www.oracle.com/goto/rac
– Using standard NFS to support
a third voting file for extended
cluster configurations (PDF)
CSSD CSSD

• Same principles apply
• Voting Disks are just
geographically dispersed


Voting Disks in Oracle ASM does not change their usage
[GRID]> crsctl query css votedisk
1. 2 1212f9d6e85c4ff7bf80cc9e3f533cc1 (/dev/sdd5) [DATA]
2. 2 aafab95f9ef84f03bf6e26adc2a3b0e8 (/dev/sde5) [DATA]
3. 2 28dd4128f4a74f73bf8653dabd88c737 (/dev/sdd6) [DATA]
Located 3 voting disk(s).

• Oracle ASM auto creates 1/3/5 Voting Files
– Voting Disks reside in one diskgroup only
– Based on Ext/Normal/High redundancy
and on Failure Groups in the Disk Group
– Per default there is one failure group per disk
– ASM will enforce the required number of disks
– New failure group type: Quorum Failgroup


35

1/20/2012

Oracle Cluster Registry (OCR) placement in Oracle ASM
• The OCR is managed like a datafile in ASM (new type)
• It adheres completely to the redundancy settings for the diskgroup (DG)
• There can be more than one OCR location in more than one DG (DG:OCR  1:1)
• Recommendation is 2 OCR locations, 1 in DATA, 1 in FRA for example


Backup of Clusteware files is fully automatic (11.2+)
• Clusterware Files (managed in ASM) enables fully Automatic Backups:
• The Voting Disks are backed up into the OCR
• Any configuration change in the cluster (e.g. node
addition) triggers a new backup of the Voting Files.
• A single, failed Voting Disks is restored by ASM
automatically within a Disk Group – no action required
• Note: Do not use DD to back up the Voting Disks anymore!

• The OCR is backed up automatically every 4 hours
• Manual Backups can be taken as required

• ONLY IF all Voting Disks are corrupted or failed
AND (all copies of) the OCR are also corrupted or unavailable
THEN manual interference would be required – the rest is automatic.


36

1/20/2012

Fencing Basics
Why are nodes evicted?
• Evicting (fencing) nodes is a preventive measure (it’s a good thing)!
• Nodes are evicted to prevent consequences of a split brain:
– Shared data must not be written by independently operating nodes
– The easiest way to prevent this is to forcibly remove a node from the cluster

1 2

CSSD CSSD


Fencing Basics
How are nodes evicted? – STONITH
• Once it is determined that a node needs to be evicted,
– A “kill request” is sent to the respective node(s)
– Using all (remaining) communication channels
• A node (CSSD) is requested to “kill itself”  “STONITH like”
– “STONITH” foresees that a remote node kills the node to be evicted

1 2

CSSD CSSD


37

1/20/2012

Fencing Basics
EXAMPLE: Network heartbeat failure
• The network heartbeat between nodes has failed
– It is determined which nodes can still talk to each other
– A “kill request” is sent to the node(s) to be evicted
 Using all (remaining) communication channels  Voting Disk(s)
 A node is requested to “kill itself”; executer: typically CSSD

1 2

CSSD CSSD

2


Fencing Basics
What happens, if CSSD is stuck?
• A node is requested to “kill itself”
• See also: MOS note
• BUT CSSD is “stuck” or “sick” (does not execute) – e.g.: 1050693.1 -
– CSSD failed for some reason Troubleshooting 11.2
– CSSD is not scheduled within a certain margin Clusterware Node
Evictions (Reboots)
 OCSSDMONITOR (was: oprocd) will take over and execute

1 2

CSSD CSSDmonitor
CSSD

2
CSSD


38

Understanding Oracle RAC 11g Release 2 Internals

Understanding Oracle RAC 11g Release 2 Internals

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