Oracle10g RAC Service Architecture

1
Oracle10g RAC Service Architecture

• Overview of Real Application Cluster Ready
  Services, Nodeapps, and User Defined Services

2
Overview

• Service Architecture
• Cluster Ready Services (CRS)
• Nodeapps
• User defined Services
• ASM Services
• Internally Managed Services
• Monitoring Services

3
RAC Service Architecture

• Oracle 10g RAC features a service based
  architecture
• This is an improvement over 9i RAC in several
  ways
• Increased flexibility
• Increased manageability
• Improvements in High Availability
• Enables 10g Grid Deployment

4
RAC Services and High Availability

• Oracle Services facilitate high availability of
  databases and related applications
• If key database resources become unavailable
  (network, storage, etc.)
• Instances and Services will be relocated to
  another node
• The failed node will be rebooted
• By default, after any server boot-up, Oracle
  attempts to restart all services on the node

5
Cluster Ready Services

• Manage the RAC Cluster
• Several Different Services
• OracleCRSService
• Oracle CSService
• OracleEVMService
• OraFenceService
• Required for RAC installation
• Installed in its own CRS_HOME

6
CRS Basics

• Used to manage RAC
• Only one set of CRS Daemons per system
• Multiple instances share the same CRS
• CRS runs as both root and Oracle users
• CRS must be running before RAC can start

7
CRS Management

• Started automatically
• Can stop and start manually
• Start the OracleCRSService
• Stop the OracleCRSService
• Uses the voting disk and OCR (Oracle Cluster
  Repository)
• Requires 3 network addresses
• Public
• Private
• Virtual Public

8
CRS Services

• OracleCRSService
• Cluster Ready Services Daemon
• OracleCSService
• Oracle Cluster Synchronization Service Daemon
• OracleEVMService
• Event Manager Daemon
• OraFenceService
• Process Monitor

9
Cluster Ready Services DaemonOracleCRSService

• Runs as Administrator user
• Automatically restarted
• Manages Application Resources
• Starts, stops and fails-over application
  resources
• Maintains the OCR (Oracle Cluster Repository)
• Keeps state information in the OCR

10
Oracle Cluster Synchronization Service
DaemonOracleCSService

• Runs as Administrator user
• Maintains the heartbeat (failure causes system
  reboot)
• Provides
• Node Membership
• Group Access
• Basic Cluster Locking
• Can integrate with 3rd party clustering products
  or run standalone
• OracleCSService also works with non-RAC systems

11
Event Manager DaemonOracleEVMService

• Runs as Administrator user
• Restarts on failure
• Generates Events
• Starts the racgevt thread to invokes Server
  Callouts

12
Process Monitor OraFenceService

• Runs as Administrator user
• Locked in memory to monitor the cluster
• Provides I/O fencing
• OraFenceService periodically monitors cluster
  status, and can reboot the node if a problem is
  detected
• An OraFenceService failure results in Oracle
  Clusterware restarting the node

13
RACG

• RACG is a behind-the-scenes process (or thread)
  that extends clusterware to support
  Oracle-specific requirements and complex
  resources.
• Runs server callout scripts when FAN events
  occur.
• Runs as processes (or threads), not as a service
  (racgmain.exe, racgimon.exe)

14
Cluster Ready ServicesManagement

• Log Files
• OracleCRSService
• ORA_CRS_HOME\log\hostname\crsd
• Oracle Cluster Registry (OCR)
• ORA_CRS_HOMElog\hostname\ocr
• OracleEVMService
• ORA_CRS_HOME\log\hostname\evmd
• OracleCSService
• ORA_CRS_HOMElog\hostname\cssd
• RACG
• ORA_CRS_HOMElog\hostname\racg

15
Nodeapp Services

• Nodeapps are a standard set of Oracle application
  services that are automatically launched for RAC
• Virtual IP (VIP)
• Oracle Net Listener
• Global Services Daemon (GSD)
• Oracle Notification Service (ONS)
• Nodeapp services run on each node
• Can be relocated to other nodes through the
  virtual IP

16
VIP (Virtual IP)

• Creates a virtual IP address used by the Listener
• The virtual IP address fails over between nodes
• Multiple virtual IP addresses can exist on the
  same system (during failover)
• Independent of the Oracle Instance
• Potential Problem if more than one database per
  node

17
Global Services Daemon (GSD)

• The daemon which executes SRVCTL commands
• GSD receives requests from SRVCTL to execute
  administrative tasks, such as startup or shutdown
• The command is executed locally on each node, and
  the results are sent back to SRVCTL.
• The daemon is installed on the nodes by default.
  It is important that you do not kill this process
  and it should not be deleted.

18
Listener

• Server-side component of Oracle Net
• Listens for incoming client connection requests
• Manages the traffic to the server when a client
  requests a network session with a server, the
  listener actually receives the request and
  brokers the client request
• If the client's information matches the
  listener's information, then the listener grants
  a connection to the server.

19
Oracle Notification Service (ONS)

• The Oracle Notification Service is installed
  automatically on each RAC node as a Node
  Application
• ONS starts automatically with each boot
• ONS uses a simple push/subscribe method to
  publish event messages to all RAC nodes with
  active ONS daemons

20
ONS and Fast Application Notification

• ONS can be configured to run on nodes hosting
  client or mid-tier applications
• ONS is the key component of Fast Application
  Notification (FAN)
• Can be utilized to extend RAC high availability
  and load balancing to mid-tier applications
• Independent of True Application Failover
• Less reliance on network configuration

21
User Defined Services

• User defined, named services may be created to
  manage database resources that are associated
  with application workloads
• One or more database instances may be mapped to a
  single service
• A database instance may be assigned to one or
  more services
• The Automated Workload Repository may be used to
  monitor Service metrics

22
User Defined Services and Failover

• Services can be defined with preferred and
  alternate instances
• A service may be assigned to start on preferred
  instances
• The same service may have alternate instances
  assigned for failover
• If multiple services are assigned for the same
  database, the preferred and alternate instance
  assignments may be different for each service

23
Automatic Storage Management Services

• Automatic Storage Management (ASM) is a storage
  option for creating and managing databases
• ASM operates like a Logical Volume Manager
  between the physical storage and the database.
• A small, automatically managed Oracle database
  instance is created on each node (if ASM is
  chosen as a storage option)
• ASM instances start automatically as Oracle
  services

24
Internally Managed Services

• When the Global Services Daemon is started as a
  part of the Node Applications, it in turn
  launches key internally managed services
• The Global Cache Service manages Cache Fusion and
  in-memory data buffers
• The Global Enqueue Service manages inter-instance
  locking and RAC recovery
• GCS and GES show up as OS processes or threads,
  but GSD is the only service that can be
  externally controlled
• GCS and GES together manage a set of virtual
  tables in memory, called the Global Resouce
  Directory

25
Global Cache Service (GCS)

• The controlling process that implements Cache
  Fusion.
• Manages the status and transfer of data blocks
  across the buffer caches of all instances.
• Tightly integrated with the buffer cache manager
  to enable fast lookup of resource information in
  the Global Resource Directory.
• Maintains the block mode for blocks in the global
  role.
• Employs various background processes (or threads)
  such as the Global Cache Service Processes (LMSn)
  and Global Enqueue Service Daemon (LMD).

26
Global Enqueue Service Monitor (LMON)

• Background process that monitors the entire
  cluster to manage global resources.
• Manages instance and process expirations and
  recovery for GCS.
• Handles the part of recovery associated with
  global resources

27
Global Resource Directory

• The data structures associated with global
  resources. It is distributed across all instances
  in a cluster.
• Global Cache Service and Global Enqueue Service
  maintain the Global Resource Directory to record
  information about resources and enqueues held
  globally.
• The Global Resource Directory resides in memory
  and is distributed throughout the cluster to all
  nodes. In this distributed architecture, each
  node participates in managing global resources
  and manages a portion of the Global Resource
  Directory.

28
Monitoring RAC Services

• ORA_CRS_HOME\bin\crs_stat
• NAMEora.rac1.gsd
• TYPEapplication
• TARGETONLINE
• STATEONLINE
• NAMEora.rac1.oem
• TYPEapplication
• TARGETONLINE
• STATEONLINE
• NAMEora.rac1.ons
• TYPEapplication
• TARGETONLINE
• STATEONLINE

29
Monitoring RAC Services

• Creating a tabular report
• ORA_CRS_HOME\bin\crs_stat -t
• Name Type Target State Host
• --------------------------------------------------
  ------------------------------------------------
• ora.rac1.gsd application ONLINE ONLINE rac1
• ora.rac1.oem application ONLINE ONLINE rac1
• ora.rac1.ons application ONLINE ONLINE rac1
• ora.rac1.vip application ONLINE ONLINE rac1
• ora.rac2.gsd application ONLINE ONLINE rac2
• ora.rac2.oem application ONLINE ONLINE rac2
• ora.rac2.ons application ONLINE ONLINE rac2
• ora.rac2.vip application ONLINE ONLINE rac2

30
Review

• What advantages does a service based architecture
  offer?
• What four services comprise Cluster Ready
  Services?
• Nodeapps consists of which four applications?
• True or False a database instance may be
  assigned to multiple services

31
Summary

• Service Architecture
• Cluster Ready Services (CRS)
• OracleCRSService
• OracleCSService
• OracleEVMService
• OraFenceService
• Nodeapps
• VIP
• Listener
• GSD
• ONS
• User defined Services
• ASM Services
• Internally managed services
• Global Cache Service
• Global Enqueue Service
• Global Resource Directory
• Monitoring Services