AskTom: How to Make and Test Your Application "Oracle RAC Ready"?
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This document discusses how to make and test applications for 'Oracle RAC Ready' status, addressing key concepts such as high availability, scalability, and optimal configurations. It highlights best practices for ensuring applications can efficiently scale on Oracle RAC systems and outlines the importance of avoiding issues like write contention. The presentation provides specific testing strategies, including utilizing Oracle RAC One Node and cloud deployments to validate RAC readiness.
![The Must Dos
Avoid Pipes
DBMS_PIPE can be
used with RAC, but
application changes
required make it work
outweigh benefits.
Use Advanced
Queuing (AQ) instead.
Use Connection Pools
Control the number of
concurrent processes
using a well-balanced
workload across nodes.
Hence, use (FAN
enabled) Connection
Pools.
Use Scalable Sequences
Use non-ordered &
cached sequences if
sequence is used to
generate primary key.
Use Scalable
Sequences (new in 18c)
[see next slide]
Avoid Write Contention
Frequent transactional
changes to the same
data blocks in all
instances may result in
“write hot spots”.
Some derivation of this
occurrence is likely the
reason for a less than
expected scaling result.
NUM
INC1()
Sequence
Connection
Pool
Next Slides
https://www.oracle.com/technetwork/database/options/clustering/overview/racappdevbp-3124851.pdf](https://image.slidesharecdn.com/makeandtestyourapplicationracready-190924191815/85/AskTom-How-to-Make-and-Test-Your-Application-Oracle-RAC-Ready-11-320.jpg)
AskTom: How to Make and Test Your Application "Oracle RAC Ready"?
- 1. Oracle OpenWorld 2019 S A N F R A N C I S C O
- 2. Ask TOM: How to Make & Test Your Application “Oracle RAC Ready” Markus Michalewicz Senior Director of Database HA & Scalability Product Management @OracleRACpm http://www.linkedin.com/in/markusmichalewicz http://www.slideshare.net/MarkusMichalewicz
- 3. Objectives for this Session • Define what “Oracle RAC Ready” actually means. • Discuss how to make your application “Oracle RAC Ready”. • Discuss how to test your application for “Oracle RAC Ready”.
- 4. “Oracle RAC Ready” Could Mean 2 Things 1 2 3 4 5 6 UCP, JDBC, ODP.Net, OCI Session Pool, Tuxedo, WebLogic ✓ High Availability / Failover 0 5000 10000 15000 20000 25000 30000 35000 40000 4 8 32 48 64 80 2035 4010 15520 22416 30016 37040 # of Cores across Oracle RAC Nodes Users 2 Nodes 3 Nodes 4 Nodes 5 NodesSAP certified SD Benchmark results Scalability
- 5. The TNS Connector String for High Availability ALIAS =(DESCRIPTION = (CONNECT_TIMEOUT=90) (RETRY_COUNT=20)(RETRY_DELAY=3) (TRANSPORT_CONNECT_TIMEOUT=3) (ADDRESS_LIST = (LOAD_BALANCE=on) ( ADDRESS = (PROTOCOL = TCP)(HOST=primary-scan)(PORT=1521))) (ADDRESS_LIST = (LOAD_BALANCE=on) ( ADDRESS = (PROTOCOL = TCP)(HOST=secondary-scan)(PORT=1521))) (CONNECT_DATA=(SERVICE_NAME = gold-cloud))) Standard for All Drivers starting with Oracle Database 12.2 https://www.slideshare.net/MarkusMichalewicz/oracle-maa-best-practices-applications-considerations
- 6. What Needs to be Configured for Continuous Availability? • RAC or RAC One, Active Data Guard, GoldenGate …Server Stack • All databases on Flex ASMFlex ASM • Services for Location TransparencyServices • Connections appear continuousContinuous Connections • FAN or 18c Database for drainingDraining • Application ContinuityInflight work continues • Drain in a timely mannerSLA’s https://www.oracle.com/technetwork/database/options/clustering/applicationcontinuity/continuous-service-for-apps-on-atpd-5486113.pdf
- 7. “Oracle RAC Ready” Usually Means 0 5000 10000 15000 20000 25000 30000 35000 40000 4 8 32 48 64 80 2035 4010 15520 22416 30016 37040 # of Cores across Oracle RAC Nodes Users 2 Nodes 3 Nodes 4 Nodes 5 NodesSAP certified SD Benchmark results Scalability
- 8. Oracle RAC Scales the World’s Most Complex Enterprise Workloads Due to its market leading Cache Fusion algorithm, Oracle RAC scales 1. any feature – e.g. Pluggable Databases, Oracle In-Memory and Oracle Data Guard 2. most enterprise applications – e.g. Ebusiness Suite, SAP, Oracle Hospitality 3. nearly all custom applications as used by many of Oracle’s >18000 RAC customers • Without the need for significant application changes • Especially on Oracle Exadata Database Machines
- 9. • Does the application scale on single (SMP) system? Scaling Principles write write write write write write write write write write write write write write write write • If it does, it is likely to scale horizontally. • Scalability is measured considering the whole system. Node 2Node 1 Node 1
- 10. Expectation: ~90% scalability rate across the system as defined Oracle RAC Scales Nearly Linearly For test and application changes • Focus on applications scaling with <80% scalability rate across the system in first go. • Best results come from application optimization. Schema optimization can complement.
- 11. The Must Dos Avoid Pipes DBMS_PIPE can be used with RAC, but application changes required make it work outweigh benefits. Use Advanced Queuing (AQ) instead. Use Connection Pools Control the number of concurrent processes using a well-balanced workload across nodes. Hence, use (FAN enabled) Connection Pools. Use Scalable Sequences Use non-ordered & cached sequences if sequence is used to generate primary key. Use Scalable Sequences (new in 18c) [see next slide] Avoid Write Contention Frequent transactional changes to the same data blocks in all instances may result in “write hot spots”. Some derivation of this occurrence is likely the reason for a less than expected scaling result. NUM INC1() Sequence Connection Pool Next Slides https://www.oracle.com/technetwork/database/options/clustering/overview/racappdevbp-3124851.pdf
- 12. New option in Create/Alter Sequence SCALE {Extend |NoExtend | NoScale } When Scale is specified an internal algorithm uses the instance id and other session specific information to generate an offset DBAs need to alter existing sequences DBA/User/ALL_sequences will reflect the additional attributes Scalable Sequences Operational Details
- 13. à Using Enterprise Manager (EM), AWR Report… How to Identify a Contention Issue? Impact of Application Contention on (index or) application data https://www.slideshare.net/MarkusMichalewicz/oracle-rac-12c-practical-performance-management-and-tuningoow13con8825 Impact of Application Contention Index Contention Block on the way from another instance Transfer delayed by log flush on other node(s) ClusterSingle Instance
- 14. Contention can occur in any multi-user system (even in Single Instance databases) Scaling out, contention can occur between instances (not only within an instance). From a contention perspective, the number of nodes is irrelevant. Contention – The Basics write write write write write write write write https://www.slideshare.net/MarkusMichalewicz/oracle-rac-internals-the-cache-fusion-edition
- 15. Frequent transactional changes to the same data blocks may result in “write hot spots” Pending redo must be written to log before the block can be transferred Contention can affect related data as much as it can affect the user data. Right growing indexes and index contention are common. In 99% of OLTP performance issues, write hot spots occur on indexes. Contention – Considerations Sequence REDO https://www.slideshare.net/MarkusMichalewicz/oracle-rac-internals-the-cache-fusion-edition
- 16. Smart Fusion Block Transfer Improves Cache Fusion latency by allowing LMS to serve dirty blocks as soon as a REDO flush is initiated Contention – Some Solutions ExaFusion Direct-to-Wire OLTP Protocol allows the database to directly call into the InfiniBand HW. 3x faster Right-Growing Index performance due to Leaf Block Split Optimizations, Scalable Sequences, Commit Cache
- 17. Contention – Another Solution: Oracle RAC 19c • Oracle RAC performance has improved up to • 5x between Oracle RAC 11.2.0.4 & 18.1 • for high contention workloads • Exadata-based optimizations: • “Smart Fusion Block Transfer” (*12.2) • Undo RDMA-Read (*18c) 5x faster
- 18. How to Test an Application “RAC Ready”? 1. Use a (dedicated / temporary) Oracle RAC test system. Ø Use Real Application Testing (RAT) to simulate load as needed. 2. Standardize on Oracle RAC One Node (http://oracle.com/goto/racone) Ø Oracle RAC One Node uses the same infrastructure as full Oracle RAC. Ø Oracle RAC One Node can be temporarily transformed into full RAC. 3. Standardize on Oracle RAC (and consolidate) Ø Use Singleton Services by default for all applications. Ø Use non-Singleton Services (temporarily) to (test) scale an application. 4. Use an Oracle RAC deployment in Oracle Cloud Ø 2-node VM and multi-node Exadata-services available. Ø Note that Autonomous Database uses Oracle RAC by default. Ø Use Zero Downtime Migration (ZDM) to move to Oracle Cloud. (http://oracle.com/goto/zdm)
- 19. Autonomous Database = RAC on Exadata (& More) Autonomous Database Automated Data Center Operations Oracle Cloud • Oracle RAC has been enhanced to meet Autonomous Transaction Processing Dedicated (ATP-D) requirements. • RAC Resource Runtime Management – allows for (memory) structures to be dynamically modified. • Colocation of workload – to define that workload should run in 1 instance independent of service • Connect_Data SESSION_SETTINGS – define actions and set set parameters as part of the connect string • More https://www.slideshare.net/MarkusMichalewicz/oracle-rac19c-the-basis-for-the-autonomous-database