1 <Insert Picture Here> Demystifying Oracle RAC Internals Barb Lundhild RAC Product Management 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.
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1
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Demystifying Oracle RAC Internals
Barb Lundhild RAC Product Management
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.
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Agenda Answer most common questions about Oracle Clusterware and Oracle RAC
• Architecture
• Oracle Clusterware – Group Membership
• Oracle Cluster Registry
• The Interconnect
• The Public Network and the Virtual IP (VIP)
• Oracle RAC Startup/Shutdown
• Advanced Features of Oracle RAC
• Appendix
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Architecture
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Service
RAC Architecture
public network
Node1
Operating System
Oracle Clusterwarecluster
interconnect
instance 1
ASM
Node n
Operating System
Oracle Clusterware
instance n
ASM
Redo / Archive logs all instances
shared storage
Database / Control files
OCR and Voting Disks
VIP1 VIPn
Managed by ASM
RAW Devices
Listener Listener
Service
What does Clusterware provide?
Operating System
Group Membership
High Availability
Framework
Process Monitor
VIP
Event Management
Oracle
Clusterware
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Oracle Clusterware Architecture
Operating System
CSS
CRS
OPROC
VIP
RACG
EVM
Oracle
Clusterware
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Oracle Clusterware
Group Membership and Heartbeats
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Oracle Clusterware Group Membership and Heartbeats
• Cluster needs to know who is a member at all times
• Oracle Clusterware has 2 heartbeats:
• Network heartbeat
If a node does not send a heartbeat for MissCount (time in
seconds), then node is evicted from cluster
• Disk heartbeat
If disk heartbeat is not updated in I/O timeout, then node is
evicted from cluster
Oracle Clusterware Split Brain Resolution
• When interconnect breaks – keeps the largest cluster
possible up, other nodes will be evicted, in 2 node cluster lowest number node remains.
• IO Fencing similar to the Stonith algorithm
• Voting disk is used to detect network problems that could
lead to a split-brain
• Final arbiter of the status of configured nodes, either up or down,
and delivers eviction notices
• Recommended to have at least 3 voting disks
• Standard NFS support for 3rd voting disk on Linux, AIX, or Solaris
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IT IS NOT SUPPORTED TO
REDUCE MISSCOUNT BELOW
THE DEFAULT (30s)
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Oracle Cluster Registry
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Oracle Cluster Registry (OCR)
• A repository containing the definition of the
configuration of the cluster and status of resources managed by the cluster
• Required file(s) for Oracle Clusterware
• Initialized during install of Oracle Clusterware
• Location defined in Registry on Windows or OCR.LOC on
Linux and Unix
• Mirrored by Oracle Clusterware or externally (RAID)
• Supports both automatic (every 4 hours) and manual
(new in 11.1) backups
• ocrconfig –manualbackup
Oracle Cluster Registry (OCR)
• Tools to manage OCR
• OCRCONFIG – command line tool to manage backups,
restore, import, export, repair, and replace
• Make sure you have a good backup before changing the
cluster configuration!
• OCRCHECK – checks integrity and displays the version of
the OCR's block format, total space available, used space,
and the OCR locations that you have configured
• OCRDUMP - view the OCR contents by writing OCR content to a file or stdout in a readable format.
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InterconnectFailure Protection and Scalability
Service
Private Interconnect
public network
Node1
Operating System
Oracle Clusterware
cluster
interconnect
instance 1
ASM
VIP1
Listener
Node 2
Operating System
Oracle Clusterware
instance 2
ASM
VIP2
Listener
Service
Switch 1 Switch 2
Node n
Operating System
Oracle Clusterware
instance n
ASM
VIPn
Listener
Service
/…/
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The Interconnect
• Interconnect is typically a standard GigE network
• IP over IB is supported
• Network should use a private dedicated non-routable switch or VLAN
• A crossover cable is not supported as an interconnect
• For high availability and scalability use OS based
solution to combine multiple physical links into a single logical link
• Same technology can be applied to public network
• Only logical link should be provided to Oracle
Clusterware and therefore Oracle RAC
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Public Network and VIPFailure Protection
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Why Oracle RAC has a VIP?
• Protects database clients from long TCP/IP timeouts
(can be >10 minutes)
• During normal operation, works the same as
hostname
• During failure, it removes network timeout from
connection request time, client fails immediately to