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Copyright © 2014 Oracle and/or its affiliates. All rights reserved. |
Oracle Database 12c with Real Application Clusters (RAC) High Availability (HA) Best Practices
Markus Michalewicz Director of Product Management Oracle Real Application Clusters July 15, 2014 @OracleRACpm http://www.linkedin.com/in/markusmichalewicz http://www.slideshare.net/MarkusMichalewicz
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Program Agenda
1
2
3
4
Introduction & Overview
Bronze-Level HA
Silver-Level HA
Gold & Platinum-Level HA
Oracle RAC & Virtualization
Additional Information
5
6
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Eliminate risk of downtime and data loss
High Availability (HA) Business Challenges
Reduce cost and increase return on investment
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
A simplified Two-Step Implementation Approach
Standardize
Set of reference
HA architectures
Reduce costs
Consolidate
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle Maximum Availability Architecture (MAA)
Edition-based Redefinition, Online Redefinition, DG / GG – Minimal downtime upgrades & migrations
Active Data Guard – Data Protection, DR – Query Offload
GoldenGate – Active-active replication – Heterogeneous
Active Replica
RMAN, Oracle Secure Backup – Backup to disk, tape or cloud
Application Continuity – Application HA
Global Data Services – Service Failover / Load Balancing
Enterprise Manager Cloud Control
– Coordinated Site Failover
RAC – Scalability – Server HA
Flashback – Human error
correction
Production Site
ASM – Storage management
Database – Core Technology
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle Database 12c MAA Four Standard Reference Architectures
GOLD Comprehensive HA and Disaster Protection Zero or near-zero data loss
SILVER High Availability (HA) for Recoverable Local Outages Data protected as of last backup
BRONZE Single Instance Database, Basic Service Restart Data protected as of last backup
PLATINUM Zero Outage for Platinum Ready Applications Zero data loss
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
BRONZE
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
SILVER
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
GOLD
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
PLATINUM
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Standardize on Clusters Clusters increase scalability and HA regardless of DB types used later
High Availability
Scal
abili
ty
License Costs
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Standardize on Oracle RAC
High Availability
Scal
abili
ty
For all the flexibility you need
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Standardize on Oracle RAC and Oracle Multitenant
High Availability
Scal
abili
ty
The new standard for consolidation
15
Commonwealth Bank
The Commonwealth Bank (CBA) is one of Australia’s leading providers of
integrated financial services including retail, business and institutional banking,
funds management, superannuation, insurance, investment and broking services.
The Bank is one of the largest listed companies on the Australian Stock Exchange.
16
Introduction
In 2007 CBA set out to create an Oracle database shared service offering for the bank
• The offering has been highly successful by several measures
• Oracle-as-a-Service has continued to be developed through several iterations
Oracle as a Service (OaaS) v1 – went live May 2008
17
Host many Oracle database applications
on a cluster of hardware
Processor consolidation
• Run each server hotter
• Take advantage of complimentary workload peaks.
Higher Availability
• Load balancing
• HA failover for component failure
• Standby DR
• Most apps do not implement these features – too expensive
Cost Reduction
Better Service
• Full time experts
• Always on-call
Reduced Risk
• Whole environment is managed
• Operated as a “business”
Oracle as a Service In A Nutshell
18
Reduce Risk, Improve Time to Market
For new Projects:
• Remove a phase from the project – infrastructure already in place
• Remove reliance on expensive/scarce SME resources for design and build
• No longer need to manage risk associated with procurement and build
• Time to instantiate a new Production quality environment: 3 months -> 2 minutes.
Example: New ISV Application introduced into our Online Share Trading platform
• Required to test performance under the workload & data volume conditions projected in 2 years time.
Dedicated Infrastructure OaaS
Implementation Time 3-4 months few hours
$ Cost to Project Several hundred thousand < $10K
On Project Completion Under-utilized asset remains Environment turned-off
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Program Agenda
1
2
3
4
Introduction & Overview
Bronze-Level HA
Silver-Level HA
Gold & Platinum-Level HA
Oracle RAC & Virtualization
Additional Information
5
6
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
BRONZE
• Minimize the cost of HA
– Use HA features included with Oracle Database
– Utilize backups to protect against media failures
– Secure offsite tape storage (in the cloud) for DR
• Optionally
– Consolidate with Oracle Multitenant
– Use VMs for dedicated resources
– Self-Service provisioning with
Enterprise Manager Database as a Service
Bronze Level High Availability
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
BRONZE
High Availability at the Bronze Tier Features Integrated with the Oracle Database
Physical Data Protection
Data Corruption Protection
& Oracle ASM (Mirroring)
Human Error Correction
Flashback Technologies: Drop, Query, Transaction, Table, and Database
Planned Maintenance
Online Redefinition
Online Reorganization
Edition Based Redefinition
Online File Move
Online Patching
Fast Backup & Recovery
Recovery Manager (RMAN)
Fast Recovery Area
Oracle Secure Backup
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle Database Inherent Protection Data Corruption Protection
• Oracle Data blocks have a well-defined structure • Block header is kept consistent with payload • Enables validation of both physical and logical intra-block consistency • Oracle ensures block validity is maintained as it traverses I/O path
• Extensive corruption checks: • DB_BLOCK_CHECKSUM: http://docs.oracle.com/cd/E11882_01/server.112/e40402/initparams049.htm • DB_BLOCK_CHECKING: http://docs.oracle.com/cd/E18283_01/server.112/e17110/initparams046.htm • For more information see My Oracle Support (MOS) note 1302539.1
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle Automatic Storage Management (ASM) 3rd Party FS Application
Automatic Storage Management
ASM Cluster & Single Node File System (ACFS)
Database
ACFS Snapshot
ASM Disk Group
DB Datafiles, OCR and Voting Files Oracle Binaries 3rd Party File Systems
Dynamic Volume Manager
ASM Instance Managing Oracle DB Files
• ASM supports ALL data – database files, file systems, Clusterware files (OCR, Voting Disk) • Built-in mirroring protects from disk failures • Auto-repair of corrupt blocks using a valid mirror copy
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Small ASM Features – Big Difference
Failure Group repair time
Similar to existing disk repair time
Default is 24 hours
Disk group attribute: failgroup_repair_time
Disk Resync
Accepts power limit
Range 1 (least resources) to 1024 (most resources)
Checkpoints: failed operations restart at the last checkpoint
Fast Disk Replacement
Efficient, atomic operation
No disk group reorganization required
Data Scrubbing
Check for logical consistency (and repair from mirror)
during rebalance
areas on demand
Protects seldom-accessed data
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Fine-grained Table Recovery From Backup using a simple RMAN command
1 0 1
0 1 0 1 0
1 1 1 0 1 0 0 1
1 0 1 1 0 1 1 1 1 0
0 0 1 0 1 0 0 0 0
1 0 0 1 1 0 1
1 0 1 0
0 1 RMAN Backups
• One simple RECOVER TABLE command to • recover one or more tables • from an RMAN backup (most recent or older)
• Eliminates time and complexity associated with manual restore, recover & export
• Enables fine-grained point-in-time recovery of • individual tables • instead of the contents of the entire tablespace.
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Cross-Platform Backup & Restore Simplified Platform Migration
1 1 1 0 1
1 0 1 1 0 1 1 1 1 0 1
0 0 1 0 1 0 0 0 0 1
1 0 0 1
1 1 1 0 1
1 0 1 1 0
1 1 1 1 0 1
0 0
1 0 1 0
0 0
0 1
1 0 0
1
Source Database (AIX)
Backup to Disk/Tape
(data files, optional endian conversion, metadata export)
Restore Backup (optional endian
conversion, metadata import)
Destination Database (Solaris)
• Simplified procedure for platform migration
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Program Agenda
1
2
3
4
Introduction & Overview
Bronze-Level HA
Silver-Level HA
Gold & Platinum-Level HA
Oracle RAC & Virtualization
Additional Information
5
6
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Program Agenda
A
B
C
Silver-Level HA
Free-of-Charge Cluster Features
Stabilize your Cluster
Oracle RAC One Node as a Standard
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
SILVER
Silver Level High Availability
• Active-passive with Oracle RAC One Node
• Automatic failover
• Fast restart on a second node
• Real-time failover & scalability with Oracle RAC
• All nodes active at all times
• Zero downtime rolling maintenance
• Hardware and OS maintenance
• For qualified Oracle Database patches
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Standardize on Clusters Clusters increase scalability and HA regardless of DB types used later
High Availability
Scal
abili
ty
License Costs
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle ASM – Overview Oracle Database 11.2 or earlier configuration
ASM Cluster Pool of Storage
Node2
Disk Group B Disk Group A
Node3 Node5 Node4
Shared Disk
Groups
Wide File Striping
One to One
Mapping of ASM
Instances to
Servers
Node1
ASM Instance
Database Instance
ASM Disk
RAC Cluster
DBA DBA DBB DBB DBC DBB
ASM ASM ASM ASM ASM
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle Automatic Storage Management (ASM) Oracle ASM 12c Standard Deployment
ASM Cluster Pool of Storage
Disk Group B Disk Group A Shared Disk
Groups
Wide File Striping
One to One
Mapping of ASM
Instances to
Servers
ASM Instance
Database Instance
ASM Disk
RAC Cluster
Node4 Node3 Node2 Node1 Node5 ASM ASM ASM ASM ASM
ASM Instance
Database Instance
DBA DBA DBC DBB DBB DBB
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Introducing Oracle Flex ASM Removal of One to One Mapping and HA
ASM Cluster Pool of Storage
Disk Group B Disk Group A
Databases share
ASM instances
ASM Instance
Database Instance
ASM Disk
RAC Cluster
Node5 Node4 Node3 Node2 Node1
Node1
runs as
ASM
Client to
Node2
Node1
runs as
ASM
Client to
Node4
Node2
runs as
ASM
Client to
Node3
ASM ASM ASM
ASM Instance
DBA DBA DBC DBB DBB DBB
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
ACFS – The ASM based Cluster File System ACFS is part of Oracle GI, hosts all data and is fully integrated
ASM Cluster Pool of Storage
Disk Group B Disk Group A
Databases share
ASM instances ASM Instance
Database Instance
ASM Disk
Cluster
Node5 Node4 Node3 Node2 Node1 ASM ASM ASM
SI
DB
RAC
DBA
RAC
DBA
RAC
DBA
Applications use
ACFS for all data
ACFS ACFS ACFS ACFS ACFS
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Program Agenda
A
B
C
Silver-Level HA
Free-of-Charge Cluster Features
Stabilize your Cluster
Oracle RAC One Node as a Standard
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Stabilize your Cluster - Reminder: Network Configuration
vixen comet
racdb1_3 racdb1_4
Oracle GI
Oracle RAC
Oracle GI
Oracle RAC
• Size Interconnect for aggregated throughput
– Foresee approx. 1Gb/sec per 32 cores
• 10GbE or IB are recommended for database consolidation and large SMP nodes (use HA)
• Bonded 1GbE with load balancing are most common and supported
– Use same type NICs for LB and failover
– Use different subnets (especially using HAIPs)
• Check for IP & NIC send and receive buffer size
• Use Jumbo frames wherever possible
• Interconnect should be stress tested usign Iperf or netperf
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Stabilize Your Cluster – Part 1 Avoid number of sessions related resource contention
vixen comet
racdb1_3 racdb1_4
Connection Pool
Oracle GI
Oracle RAC
Oracle GI
Oracle RAC
• Control the number of concurrent sessions • Foreground processes are in time-share class • Scheduling delays on high context switch rates on busy systems may increase the variation in the cluster traffic times • More processes imply higher memory utilization and higher risk of paging
•How to control concurrent sessions: • Use connection pooling • Avoid connection storms (pool and process limits )
• Ensure that load is well-balanced over nodes
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Stabilize Your Cluster – Part 2 Optimize memory locally
• Avoid memory pressure!
– Paging and Swapping activity on one node affects performance on all nodes
– Severe Paging and Swapping activity on one node can cause instance evictions
• #1 cause for service disruptions in clusters
• Use Memory Guard
– Oracle Quality of Service Management (QoS) feature – available in monitoring only mode
– Prevents new connections from coming in to a server that is already under memory pressure
vixen comet
racdb1_3 racdb1_4
Oracle GI
Oracle RAC
Oracle GI
Oracle RAC
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Stabilize Your Cluster – Part 3 Use Solid State Disks to host swap space
• Use Solid State Disks (SSDs) to host swap space in order to increase node availability
– Memory pressure can cause node evictions.
– Preventing memory pressure is the solution.
– If prevention is not successful and swapping is performed by the Operating System (OS),
• hosting the swap space can mitigate the impact that extensive swapping can have on cluster operations on the on the affected server(s).
• More information:
– My Oracle Support Note Doc ID: 1671605.1 – “Use Solid State Disks to host swap space in order to increase node availability”
vixen comet
racdb1_3 racdb1_4
Oracle GI
Oracle RAC
Oracle GI
Oracle RAC
Swapping
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Stabilize Your Cluster – Part 4 Configure Huge Pages for Oracle RAC
• Use Huge pages for SGA (Linux)
– Dramatic reduction in memory for page tables
– SGA pages pinned in memory
• More information:
– My Oracle Support note 361323.1 – HugePages on Linux: What It Is... and What It Is Not...
– My Oracle Support note 401749.1 – Shell Script to Calculate Values Recommended Linux HugePages / HugeTLB Configuration
• Engineered systems provide templates for pre-configuration of huge pages for the SGA
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Program Agenda
A
B
C
Silver-Level HA
Free-of-Charge Cluster Features
Stabilize your Cluster
Oracle RAC One Node as a Standard
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle RAC One Node Oracle RAC One Node 12c provides:
1. Best in-class single instance Oracle Database availability
2. Better database consolidation
3. Better database virtualization
Using
• A standardized and improved deployment and management
• A familiar and matured HA stack
• Oracle Grid Infrastructure
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle RAC One Node Basic Features • Oracle RAC One Node is
– an Oracle RAC enabled database
– with only one instance running under normal operation
• In case of a server or instance failure, the one running instance is started on another server in the cluster (failover)
• Online Database Relocation (Oracle RAC One Node specific feature) minimizes downtime during scheduled maintenance operations.
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle RAC One Node vs. Oracle RAC “Always On” vs. “Always Running”
Oracle RAC One Node: one instance
per database running at a time
Oracle RAC: multiple instances
per database running concurrently
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Online Database Relocation for better HA Oracle RAC One Node-specific functionality that makes the difference
Node3 Node2
Oracle (Flex) ASM based pool of shared storage
Node1
Public Network
DBB DBC
Oracle Grid Infrastructure
DBE DBD
DBA
DBA Online DB Relocation
•Online Database Relocation minimizes downtime during (scheduled) maintenance operations such as:
•Patching
•Resource re-allocation due to demand
http://www.oracle.com/goto/racone
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Standardize on Oracle RAC (One Node) To simplify Oracle RAC testing
vixen comet
RON RON_2
Online upgrade
RON_1
AWR ---
ASH
AWR ---
ASH
Decide
Oracle GI
Oracle RAC
Oracle GI
Oracle RAC
Oracle RAC testing made simple:
1. Standardize on Oracle RAC (One Node)
2. Run tests on Oracle RAC One Node instance
• RAC One Node behaves basically like a single instance
3. Online Upgrade to Oracle RAC for testing only
4. Run tests on Oracle RAC
5. Decide whether the application provides service goals when load balanced over multiple active instances
• Identify bottlenecks and tuning actions as required
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Standardize on Oracle RAC (One Node) The simplest way of converting to RAC: unplug/plug
Node2
CDB Instance 2
Node1
CDB Instance 1
CDB
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle RAC Oracle RAC 12c provides:
1. Better Business Continuity and High Availability (HA)
2. Agility and Scalability
3. Cost-effective Workload Management
Using
• A standardized and improved deployment and management
• A familiar and matured HA stack
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Program Agenda
1
2
3
4
Introduction & Overview
Bronze-Level HA
Silver-Level HA
Gold & Platinum-Level HA
Oracle RAC & Virtualization
Additional Information
5
6
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Oracle Database 12c MAA Four Standard Reference Architectures
GOLD Comprehensive HA and Disaster Protection Zero or near-zero data loss
SILVER High Availability (HA) for Recoverable Local Outages Data protected as of last backup
BRONZE Single Instance Database, Basic Service Restart Data protected as of last backup
PLATINUM Zero Outage for Platinum Ready Applications Zero data loss
✔ ✔
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
GOLD
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
PLATINUM
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Program Agenda
1
2
3
4
Introduction & Overview
Bronze-Level HA
Silver-Level HA
Gold & Platinum-Level HA
Oracle RAC & Virtualization
Additional Information
5
6
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
This is Oracle RAC
Storage Management
1. Oracle ASM
2. Oracle ACFS
Quality of Service
1. Quality of Service Management (QoS)
2. Application Continuity
High Availability and Scalability
1. Oracle Clusterware
2. Oracle RAC (One Node)
Consolidation
1. Oracle RAC with Oracle Multitenant
Core
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Optimizing the use of DBs in virtual environments
Bare-Metal Server
DOM-0 Hypervisor
Guest
Dom-0
Guest
Bare-Metal Server
DOM-0 Hypervisor
Dom-0
Guest Guest
DBC1 DBA1
+1
DBC2 DBA2
+1
Oracle RAC provides additional benefit in any virtual environment
Core
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Optimizing the use of DBs in virtual environments
Guest Guest Guest Guest
DBC1 DBA1
+1
DBC2 DBA2
+1
Core
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Providing an alternative to virtual environments
Node1 Node2 NodeN Node..
DBC1 DBA1 DBC2 DBA2
+1 +1
Core
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Program Agenda
1
2
3
4
Introduction & Overview
Bronze-Level HA
Silver-Level HA
Gold & Platinum-Level HA
Oracle RAC & Virtualization
Additional Information
5
6
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Tools for a Lasting HA Experience
dasher dancer
vixen comet
LOGGERD
sysmond
sysmond
Oracle GI Oracle GI
Oracle GI Oracle GI
sysmond
sysmond
sysmond
LOGGERD
Cluster Health Monitor (CHM) – CHM/OS
1. First failure diagnostics: Collects as much system metrics and data as feasible
2. Collects system metrics on all nodes in the cluster synchronized
3. Persistent storage of all collected data in a database
4. Integrated with Oracle Grid Infrastructure starting with 11.2.0.2 (12c: uses GIMR)
5. Robust collection in situations of resource starvation
6. Data dump or visualization
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
Tools for a Lasting HA Experience
Guest Guest Guest
DBC1 DBA1 DB DBA2
• Trace File Analyzer (TFA) – Improved comprehensive
first failure diagnostics collection
– Efficient collection, packaging and transfer of data for customers
– Collect for all relevant components (OS, Grid Infra., ASM, RDBMS)
– One command to collect all information
– More information: MOS note ID 1513912.1
• OraChk (formerly RACcheck)
– RAC Configuration Audit Tool
– For details see MOS note ID 1268927.1
– Checks the Oracle Database:
– Standalone Database
– Grid Infrastructure & RAC
– Maximum Availability Architecture (MAA) Validation
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
More Information: www.oracle.com/goto/rac
• Presentations: •Oracle RAC 12c Collaborate Best Practices
•http://www.slideshare.net/MarkusMichalewicz/oracle-rac-12c-collaborate-best-practices-ioug-2014-version
•Oracle RAC 12c Practical Performance Management and Tuning •http://www.slideshare.net/MarkusMichalewicz/oracle-rac-12c-practical-performance-management-and-tuningoow13con8825
•The Oracle RAC Family of Solutions •http://www.slideshare.net/MarkusMichalewicz/the-oracle-real-application-clusters-rac-family-of-solutions
• White Papers: •Oracle RAC 12c Best Practices
•http://www.slideshare.net/MarkusMichalewicz/oracle-rac-12c-best-practices
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
• Database and Middleware streams available
• Videos
– Feature different groups and presenters
– Cover a broad range of topics and products
• Oracle RAC PM / Dev contributions so far:
– Oracle Flex Cluster: Optimized Resource Management for the Cloud - Ian Cookson
– Oracle Grid Infrastructure 12c Bundled Agents – Shankar Iyer
– ACFS Product Overview and Use Cases - Ara Shakian
– The Oracle Real Application Clusters (RAC) Family of Solutions - A User Guide – Markus M.
– Next Generation Oracle Automatic Storage Management - Jim Williams
– Implementing DBaaS with Oracle RAC 12c and Quality of Service Management - Mark Scardina
– Oracle RAC Practical Performance Management and Tuning – Markus Michalewicz
Oracle Learning Streams: http://education.oracle.com/streams/
Copyright © 2014 Oracle and/or its affiliates. All rights reserved.
• Presentation: Oracle RAC on Extended Distance Clusters – http://www.slideshare.net/MarkusMichalewicz/oracle-rac-on-extended-distance-clusters
• WP: Oracle Real Application Clusters on Extended Distance Clusters – http://www.oracle.com/technetwork/database/options/clustering/overview/extendedracversion11-435972.pdf
• WP: Using standard NFS to support a third voting file for extended cluster configurations
– http://www.oracle.com/technetwork/database/database-technologies/clusterware/overview/grid-infra-thirdvoteonnfs-131158.pdf
• Presentation: Oracle Clusterware Node Management and Voting Disks – http://www.slideshare.net/MarkusMichalewicz/oracle-clusterware-node-management-and-voting-disks
More Information: www.oracle.com/goto/rac