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ORACLE 11G REAL APPLICATION CLUSTERS
ADVANCED ADMINISTRATION
Natik Ameen
Session #352
Introduction
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Natik Ameen, Senior Oracle DBA
DBA for 8 years, with 4 years on RAC 9i, 10g
Financial, Gaming and Aviation industries
Intended for everyone who has basic knowledge of RAC
Objective
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RAC overview
ASM
Nodeapps
Metrics collection
Wait events
Best Practice
11g New features
RAC Overview
• Clustered nodes
• Cluster Interconnect
• Virtual IP
• Shared storage
• NodeApps
RAC Architecture
• Clustered nodes
• Interconnect Network
• Shared storage
SGA Structure & Processes
Node 1
LMON
LMD0
Node 2
DIAG
LMON
Global Resource Directory
LMD0
DIAG
Global Resource Directory
Dictonary Cache
Dictonary Cache
Buffer
Cache
Buffer
Cache
Interconnect
Log Buffer
Log Buffer
LCK0
LGWR
DBW0
LCK0
LGWR
DBW0
LMS0
SMON
PMON
LMS0
SMON
PMON
Shared Storage
• Global Resource Directory : Maintains mapping of data in SGA
• Global Cache Server: Synchronizes Buffer cache across instances
• Global Enqueue Services: Maintains coherency in data dictionary &
library caches
• Lock Manager Server: Transports blocks for Cache Fusion between
nodes.
Cache Fusion
• What is it
• Concurrency & Consistency
• Scalability
Interconnect Network
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Main component for “Cache Fusion”
IC uses private network
User Datagram Protocol(UDP)
Reliable Datagram Socket Protocol(RDS) > 10.2.0.3
Typical bandwidth utilization 20-30%, saturated > 70%
ASM Overview
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ASM Instance
Disk Group
Disk Files
ASMLib
ASM Instance
• Scaled down version of DB instance
• DB instance access DB files
Disk Groups
• Striping
• Mirroring
• Failure groups
ASM Files
• Name pre-pended with ‘+’
ASMLib
• Kernel driver with efficient access to DB files
NodeApps
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Listener
Oracle Notification Services
Fast Application Notification
Fast Connection Failover
Metrics Collection
• AWR Reports
• OS Utilities
• Bench Marking
AWR Report
The RAC specific statistics include:
• Instance Global Cache Load Profile
• Global Cache Efficiency percentages
• Messaging Statistics
• Top % CR and Current Block Segments
Cache Fusion data block & messaging traffic
Calculate network traffic
RAC Wait Events
Most of these wait events occur during Cache Fusion
• GC cr/current block 2-way, 3-way
• GC cr/current block congested
• GC cr/current block busy
• GC current grant busy
• GC cr/current block request
• GC cr block lost
GC wait events
• Classified under “cluster wait lass”.
• Characterized as “current” or as “CR”.
• “current” classified as all blocks read into memory
for the very first time
• CR denotes block for read access
• Master node maintains complete information on the
resource, others maintain information on locally
held locks
gc current block 2-way
A requests block from Master B
"gc curent request" event on A
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Instance A
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gc current block 2-way
Instance B
Instance B finds block & sends to A
Instance A requests block from master instance B
If the block is available on B then it is sent to A
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gc current block 3-way
A requests block from Master B
"gc curent request" event on A
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Instance A
4
gc current block 3-way
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B Forwards request to C
Instance B
Instance C
C sents block to A 3
• Instance A requests block from master instance B
• B does not have block but directs instance holding block
or directs request to disk
• Three hops maximum, not dependant on number of nodes
GC cr/current block congested
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Repeated requests by foreground processes, not serviced by LMS
Indicates LMS not able to keep up
Queue lengths & scheduling delays in OS, can cause LMS delays
GC cr/current block busy
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Delay for some reason, before block sent to requestor
Could be due to I/O saturation
GC current grant busy
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Permission to access the block granted, but blocked by other requests ahead of it
GC cr/current block request
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Wait time, when cr or current block is being retrieved
GC block lost
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Lost blocks possibly due to faulty interconnect network
Where to get more information
• Other sessions here at IOUG-A Live!
• RAC Special Insterest Group(RAC SIG)
• Consulting companies (depending on specialization)
Questions?
• Lots of things to cover
• If we didn’t cover something you wanted to hear,
please contact me
ORACLE 11G REAL APPLICATION CLUSTERS
ADVANCED ADMINISTRATION
THANK YOU!
Please fill out evaluations!