<Insert Picture Here>

Demystifying Oracle RAC Internals
Barb Lundhild RAC Product Management

The following is intended t...
Agenda
Answer most common questions about
Oracle Clusterware and Oracle RAC
<Insert Picture Here>

•
•
•
•
•
•
•
•

Archit...
RAC Architecture
public network

VIP1
Service

VIPn
Service

Listener

Listener

instance 1

instance n

ASM

ASM

Node1

...
Oracle Clusterware Architecture

VIP

EVM
Oracle
Clusterware

RACG
CRS
OPROC
CSS
Operating System

<Insert Picture Here>

...
Oracle Clusterware
Group Membership and Heartbeats
• Cluster needs to know who is a member at all times
• Oracle Clusterwa...
IT IS NOT SUPPORTED TO
REDUCE MISSCOUNT BELOW
THE DEFAULT (30s)

<Insert Picture Here>

Oracle Cluster Registry

6
Oracle Cluster Registry (OCR)
• A repository containing the definition of the
configuration of the cluster and status of r...
<Insert Picture Here>

Interconnect
Failure Protection and Scalability

Private Interconnect
/…/
public network

Node1

VI...
The Interconnect
• Interconnect is typically a standard GigE network
• IP over IB is supported

• Network should use a pri...
Why Oracle RAC has a VIP?
• Protects database clients from long TCP/IP timeouts
(can be >10 minutes)
• During normal opera...
Oracle RAC VIP is DIFFERENT
• Only accepts connections when on its home node
• Failure on home node: relocates to another ...
Listener.ora
SID_LIST_LISTENER_PMRAC1 =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = /u01/oracle/product...
Application VIPs
• New resource as of Oracle RAC 10g Release 2
• Created as functional VIPs which can be used to
connect t...
<Insert Picture Here>

Oracle RAC
Startup/Shutdown

Node Startup Sequence
VIP1
Service
Listener
Instance 1
ASM
Oracle Clus...
Oracle Dependencies
public network

VIP1 VIP2
Service

Listener

Listener

instance 1

instance 2

ASM

Node1

VIP1
Servic...
<Insert Picture Here>

Advanced Features of RAC
High Availability and Load
Balancing for Applications

Services
• Applicat...
Cluster Managed Services
• Service has a set of resources defined to Oracle
Clusterware
• Oracle Clusterware manages start...
Oracle Notification Service (ONS)
• Publish/Subscribe Messaging System
• Allows both local and remote consumption
• Used b...
Fast Connection Failover
• Fast and reliable high availability for connections in an
Oracle Real Application Clusters 10g ...
Runtime Connection Load Balancing
• When application does “getConnection”, the
connection given is the one that will provi...
Leverage XA Connection Affinity
New with 11.1.0.7
• DB 11g fixes the correctness problem. XA Affinity
adds Performance and...
<Insert Picture Here>

Appendix

For More Information

http://search.oracle.com
REAL APPLICATION CLUSTERS

or
otn.oracle.c...
Useful Metalink Notes
• Note 342082.1 “How to Change Subnet Masks for VIPs”
• Note 294430.1 “CSS Timeout Computation in RA...
24
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Racsig rac internals

  1. 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. 1
  2. 2. Agenda Answer most common questions about Oracle Clusterware and Oracle RAC <Insert Picture Here> • • • • • • • • 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 <Insert Picture Here> Architecture 2
  3. 3. RAC Architecture public network VIP1 Service VIPn Service Listener Listener instance 1 instance n ASM ASM Node1 Node n cluster Oracle Clusterware interconnect Oracle Clusterware Operating System Operating System shared storage Managed by ASM RAW Devices Redo / Archive logs all instances Database / Control files OCR and Voting Disks What does Clusterware provide? VIP Event Management Oracle High Availability Framework Clusterware Process Monitor Group Membership Operating System 3
  4. 4. Oracle Clusterware Architecture VIP EVM Oracle Clusterware RACG CRS OPROC CSS Operating System <Insert Picture Here> Oracle Clusterware Group Membership and Heartbeats 4
  5. 5. 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 5
  6. 6. IT IS NOT SUPPORTED TO REDUCE MISSCOUNT BELOW THE DEFAULT (30s) <Insert Picture Here> Oracle Cluster Registry 6
  7. 7. 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. 7
  8. 8. <Insert Picture Here> Interconnect Failure Protection and Scalability Private Interconnect /…/ public network Node1 VIP1 Service VIP2 Service Listener Listener Listener instance 1 instance 2 instance n Node 2 VIPn Service ASM ASM ASM Oracle Clusterware Oracle Clusterware Oracle Clusterware Operating System Operating System Node n Operating System Switch 1 Switch 2 cluster interconnect 8
  9. 9. 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 <Insert Picture Here> Public Network and VIP Failure Protection 9
  10. 10. 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 next address in the list sales.us.acme.com =(DESCRIPTION=(ADDRESS_LIST= (LOAD_BALANCE=on)(FAILOVER=ON) (ADDRESS=(PROTOCOL=tcp)(HOST=sales1-vip)(PORT=1521)) (ADDRESS=(PROTOCOL=tcp)(HOST=sales2-vip)(PORT=1521))) (CONNECT_DATA= (SERVICE_NAME= sales.us.acme.com))) Oracle RAC VIP The Details • • • • One for each node in cluster Required for Oracle Clusterware installation IP and network name should not currently be in use Should be registered in DNS and must be on the same subnet as public IP address • Configuration managed by VIPCA and SRVCTL • Note that netmask defaults to 255.255.255.0, rather than defaulting to netmask of underlying physical interface. 10
  11. 11. Oracle RAC VIP is DIFFERENT • Only accepts connections when on its home node • Failure on home node: relocates to another node in the cluster only to send a error back to client (it will not be in the listener so connections are not accepted!) • You will only have one active RAC VIP per node (there may be others who have relocated due to failure!) • Independent of number of databases running in cluster Oracle RAC VIP [root@pmrac1 root]# ifconfig eth0 Link encap:Ethernet HWaddr 00:12:79:D8:90:93 inet addr:144.15.214.10 Bcast:144.15.215.255 Mask:255.255.252.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5070815 errors:0 dropped:0 overruns:0 frame:0 TX packets:3064435 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:509963813 (486.3 Mb) TX bytes:3621223517 (3453.4 Mb) Interrupt:25 eth0:1 Link encap:Ethernet HWaddr 00:12:79:D8:90:93 inet addr:144.15.214.30 Bcast:144.15.215.255 Mask:255.255.252.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5762695 errors:0 dropped:0 overruns:0 frame:0 TX packets:5679252 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:3400642002 (3243.1 Mb) TX bytes:3166774792 (3020.0 Mb) Interrupt:25 11
  12. 12. Listener.ora SID_LIST_LISTENER_PMRAC1 = (SID_LIST = (SID_DESC = (SID_NAME = PLSExtProc) (ORACLE_HOME = /u01/oracle/product/10gR2/asm) (PROGRAM = extproc) ) ) LISTENER_PMRAC1 = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1)) (ADDRESS = (PROTOCOL = TCP)(HOST = pmrac1-vip)(PORT = 1521)(IP = FIRST)) (ADDRESS = (PROTOCOL = TCP)(HOST = 144.25.214.45)(PORT = 1521)(IP = FIRST)) ) ) Use the VIP in the Address List Automatically completed by DBCA • init.ora remote_listener = listeners_sales local_listener = listeners_sales1 • tnsnames.ora in RAC ORACLE_HOME LISTENERS_SALES = (ADDRESS_LIST = (ADDRESS = (PROTOCOL (ADDRESS = (PROTOCOL (ADDRESS = (PROTOCOL ) LISTENERS_SALES1 = (ADDRESS_LIST = (ADDRESS = (PROTOCOL ) = TCP)(HOST = node1-vip)(PORT = 1521)) = TCP)(HOST = node2-vip)(PORT = 1521)) = TCP)(HOST = node3-vip)(PORT = 1521)) = TCP)(HOST = node1-vip)(PORT = 1521)) 12
  13. 13. Application VIPs • New resource as of Oracle RAC 10g Release 2 • Created as functional VIPs which can be used to connect to an application regardless of the node it is running on • VIP is a dependent resource of the user registered application • There can be many VIPs, one per User Application Creating an Application VIP • The usrvip script must run as root • The default permissions need to be changed after registration • As root… crs_setperm ApplicationVIP1 –o root • Allow oracle user to execute this script • As root… crs_setperm ApplicationVIP1 –u user:oracle:r-x • Start the VIP • As oracle… crs_start ApplicationVIP1 13
  14. 14. <Insert Picture Here> Oracle RAC Startup/Shutdown Node Startup Sequence VIP1 Service Listener Instance 1 ASM Oracle Clusterware Operating System 14
  15. 15. Oracle Dependencies public network VIP1 VIP2 Service Listener Listener instance 1 instance 2 ASM Node1 VIP1 Service ASM Node 2 cluster Oracle Clusterware interconnect Oracle Clusterware Operating System Operating System shared storage Redo / Archive logs all instances Managed by ASM Database / Control files RAW Devices OCR and Voting Disks Oracle Dependencies Prior to 10.2.0.3 public network VIP1 VIP2 Service Listener Listener instance 1 instance 2 ASM Node1 VIP1 Service ASM Node2 cluster Oracle Clusterware interconnect Oracle Clusterware Operating System Operating System shared storage Managed by ASM RAW Devices Redo / Archive logs all instances Database / Control files OCR and Voting Disks 15
  16. 16. <Insert Picture Here> Advanced Features of RAC High Availability and Load Balancing for Applications Services • Application workloads can be defined as Services Individually managed and controlled Assigned to instances during normal startup On instance failure, automatic re-assignment Service performance individually tracked Finer grained control with Resource Manager Integrated with other Oracle tools / facilities (E.G. Scheduler, Streams) • Managed by Oracle Clusterware • Several services created and managed by database server • • • • • • Many features discussed do not apply to default database service 16
  17. 17. Cluster Managed Services • Service has a set of resources defined to Oracle Clusterware • Oracle Clusterware manages start/stop/re-locate based on definition • Define Preferred (normal operations) and Available (if failure occurs) instances • Dependent on Instance and VIP • Manage using Enterprise Manager • SRVCTL CLI for Cluster configuration • DBMS_SERVICE PL/SQL package What is FAN? • Fast Application Notification (FAN) is a RAC notification mechanism • FAN HA Events: Notification of Up/Down for service, instance & node • Load Balancing Advisory Events: Advise clients of current load for service and where to send connection requests • Enable it, and Forget it. 17
  18. 18. Oracle Notification Service (ONS) • Publish/Subscribe Messaging System • Allows both local and remote consumption • Used by Fast Application Notification (FAN) to publish HA Events and Load Balancing Events • Used by FAN clients to subscribe to events • Automatically installed and configured by the installation of Oracle Clusterware • DO NOT TURN OFF – Required by Oracle Clusterware and RAC Fan Clients • HA Events: JDBC Implicit Connection Cache, OCI, ODP.NET Connection Pools, Listener, Server Side Callouts, CMAN • Load Balancing Advisory Events: JDBC Implicit Connection Cache, ODP.NET Connection Pools, Listener, CMAN • New with 11.1.0.7: Universal Connection Pool for JAVA 18
  19. 19. Fast Connection Failover • Fast and reliable high availability for connections in an Oracle Real Application Clusters 10g environment • Enable it and forget it • Application can make it transparent to user by trapping SQL Exception and retrying • Supported by Oracle JDBC, OCI, and ODP.NET Load Balancing Advisory • Load Balancing Advisory is an advisory for balancing work across RAC instances. • Load Balances at the transaction level (not connections!) • Directs work to where services are executing well and resources are available. • Adjusts distribution for different power nodes, different priority and shape workloads, changing demand. • Stops sending work to slow, hung, failed nodes early. 19
  20. 20. Runtime Connection Load Balancing • When application does “getConnection”, the connection given is the one that will provide the best service. • Supported by Oracle JDBC, OCI, and ODP.NET connection Pools • Policy defined by setting GOAL on Service • Need to have Oracle Net Services Connection Load Balancing Leverage Temporal Connection Affinity New with 11.1.0.7 RAC Database Web Client Connect to me Instance1 Instance2 Pool Connection Affinity Context Instance3 20
  21. 21. Leverage XA Connection Affinity New with 11.1.0.7 • DB 11g fixes the correctness problem. XA Affinity adds Performance and Scalability. • Eliminates current single DTP service limitation for XA/RAC • XA affinity is the ability to automatically localize a global transaction to a single RAC instance • Scope is the life of a global transaction • • First connection request for a global transaction uses Runtime Connection Load Balancing (RCLB) Subsequent requests use affinity and are routed to the same RAC instance where XA first started Q & A QUESTIONS ANSWERS 21
  22. 22. <Insert Picture Here> Appendix For More Information http://search.oracle.com REAL APPLICATION CLUSTERS or otn.oracle.com/rac 22
  23. 23. Useful Metalink Notes • Note 342082.1 “How to Change Subnet Masks for VIPs” • Note 294430.1 “CSS Timeout Computation in RAC 10g ” • Note 284752.1 “10g RAC: Steps To Increase CSS Misscount, Reboottime and Disktimeout” • Note 291962.1 ‘Setting Up Bonding in SLES 9’ • Note 291958.1 ‘Setting Up Bonding in Suse SLES8’ • Note 298891.1 ‘Configuring Linux for the Oracle 10g VIP using bonding’ • Note 283107.1 ‘Configuring Solaris IP Multipathing (IPMP) for the Oracle 10g VIP’ OTN.ORACLE.COM/RAC • Workload Management with Oracle Real Application Clusters (FAN, FCF, Load Balancing) • Using standard NFS to support a third voting disk on a stretch cluster configuration on Linux • Using Oracle Clusterware to Protect 3rd Party Applications • New: otn.oracle.com/clusterware • RAC Sample Code Page http://www.oracle.com/technology/sample_code/products/rac/index.html 23
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