Bài giảng Oracle database high availability

ORACLE DATABASE HIGH AVAILABILITY*OUTLINEOverview Of High AvailabilityOracle Database High Availability ArchitectureDetermining Your High Availability Requirements *OVERVIEW OF HIGH AVAILABILITYWhat is Availability ?Availability is the degree to which an application, service, or functionality is available upon user demand.Main characteristics of Availability:Reliability: system must have less errors in both hardware and software – including database, web servers, and application.*OVERVIEW OF HIGH AVAILABILITYRecoverability: there may have many choices in recovering from a failure. Hence, the most appropriate action is also to satisfy business requirements mostTimely error detection: although a system can be recovered from an outage in time manner, time to monitor corrupt components can be costly and cause your SLA (service level agreement) not met.Continuous operation: maintenance activities should be allowed to perform continuous data access with little or no downtime and transparent to end users.*OVERVIEW OF HIGH AVAILABILITYImportance Of High AvailabilitySupport enterprises to gain their competitive advantages by providing capability of continuously accessing to critical business data.Much downtime (surpass the threshold) can causeDirect cost: lost productivity, lost revenue.Indirect cost: damaged customer relationships, bad publicity, and lawsuits. *OVERVIEW OF HIGH AVAILABILITYCauses Of DowntimeUnplanned:Computer failureStorage failureHuman errorData corruptionSite failurePlanned:System changesData changes*OVERVIEW OF HIGH AVAILABILITYCauses Of DowntimeUnplanned:Computer failureA computer failure outage occurs when the system running the database becomes unavailable because it has shut down or is no longer accessible.Example: Database system hardware failure Operating system failure Oracle instance failure Network interface failure*OVERVIEW OF HIGH AVAILABILITYCauses Of DowntimeUnplanned:Storage failure A storage failure outage occurs when the storage holding some or all of the database contents becomes unavailable because it has shut down or is no longer accessible.Example: Disk drive failure Disk controller failure Storage array failure*OVERVIEW OF HIGH AVAILABILITYCauses Of DowntimeUnplanned:Human error A human error outage occurs when unintentional or malicious actions are committed that cause data within the database to become logically corrupt or unusable.Example: Dropped database object Inadvertent data changes Malicious data changes*OVERVIEW OF HIGH AVAILABILITYCauses Of DowntimeUnplanned:Site failureA site failure outage occurs when an event causes all or a significant portion of an application to stop processing or slow to an unusable service levelExample: Site-wide network failure Natural disaster Terrorist or malicious attack on operations or the site*OVERVIEW OF HIGH AVAILABILITYCauses Of DowntimePlanned:System changesPlanned system changes occur when performing routine and periodic maintenance operations and new deployments.Example: Adding/removing processors to/from an SMP server Adding/removing nodes to/from a cluster*OVERVIEW OF HIGH AVAILABILITYCauses Of DowntimePlanned:Data changesPlanned data changes occur when there are changes to the logical structure or physical organization of Oracle database objects.Example: Table definition changes Creating and rebuilding indexes*ORACLE DATABASE HIGH AVAILABILITY ARCHITECTUREOracle Database 10gOracle Flashback TechnologyAutomatic Storage ManagementRecovery ManagerFlash Recovery AreaOnline Reorganization and RedefinitionOracle Database 10g with RACOracle Database 10g with Data GuardOracle Database 10g with RAC and Data Guard – MAAOracle Database 10g with Streams*STANDARD ORACLE DATABASE 10G HIGH AVAILABILITYOracle Flashback Technology*The flashback features offer the capability to query past versions of schema objects, query historical data, perform change analysis.*Flashback technology includes the following features:Oracle Flashback QueryOracle Flashback Versions QueryOracle Flashback Transaction QueryOracle Flashback TableOracle Flashback DropOracle Flashback DatabaseOracle Flashback Restore Points*STANDARD ORACLE DATABASE 10G HIGH AVAILABILITYAutomatic Storage Management (ASM)ASM spreads files across all available storage and mirror at the database file level rather than the entire disk level.ASM simplifies the processes of setting up mirroring, adding disks, and removing disksInstead of managing hundreds and possibly thousands of files (as in a large data warehouse), DBAs using ASM create and administer a larger-grained object—the disk group—which identifies the set of disks that will be managed as a logical unit. *STANDARD ORACLE DATABASE 10G HIGH AVAILABILITYAutomatic Storage Management (ASM)With ASM mirroring, an additional level of data protection can be provided with the use of failures groups. *STANDARD ORACLE DATABASE 10G HIGH AVAILABILITYMirroring OptionDescription2-way mirroringEach extent has 1 mirrored copy.3-way mirroringEach extent has 2 mirrored copies.UnprotectedASM provides no mirroring. Used when mirroring is provided by the disk subsystem itself.ASM Mirroring Options*STANDARD ORACLE DATABASE 10G HIGH AVAILABILITYMirroring Options for Each Disk Group TypeDisk Group TypeSupported Mirroring LevelsDefault Mirroring LevelNormal redundancy2-way3-wayUnprotected (none)2-wayHigh redundancy3-way3-wayExternal redundancyUnprotected (none)Unprotected*STANDARD ORACLE DATABASE 10G HIGH AVAILABILITYRecovery ManagerRecovery Manager is an Oracle utility to manage the backup and, more importantly, the recovery of the database.RMAN provides the following benefits:Automatic failover to a previous backup when the restore operation discovers a missing or corrupt backup.Automated recovery through a previous point-in-time recovery.Fast incremental backups using block change tracking.Retention policy ensures that relevant backups are retained*STANDARD ORACLE DATABASE 10G HIGH AVAILABILITYFlash Recovery AreaThe flash recovery area is a unified storage location for all recovery-related files and activities in an Oracle database.All RMAN backups, archive logs, control file autobackups, and datafile copies are automatically written to a specified file system or ASM disk group.*STANDARD ORACLE DATABASE 10G HIGH AVAILABILITYOnline Reorganization and RedefinitionOne way to enhance availability and manageability is to allow users full access to the database during a data reorganization operation.Online architecture provides the following benefits:Tables can be reorganized and redefined online: any physical or logical attribute of the table can be changed online.All index operation can be performed onlineOnline move of a partitioned table.*ORACLE DATABASE 10G WITH RACOracle Database 10g with RAC architecture uses Real Application Clusters and is an inherently high availability system*ORACLE DATABASE 10G WITH RACThis architecture provides the following benefits:Fast node (measured in minutes) and instance failover (measured in seconds)Rolling patch upgrades Multiple active instance availability and scalability across multiple nodes *ORACLE DATABASE 10G WITH DATA GUARD Data Guard provides a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases to enable Oracle databases to survive disasters and data corruption.Two type of standby databases:Physical standby databaseLogical standby database*ORACLE DATABASE 10G WITH DATA GUARDPhysical standby database provide these advantages:Protection from user errors and logical corruptionProtection from disasters and site failures if located remotelyStandby database can diverge for reporting or testing purposes and resynchronize with its primary database once completeBackups can be taken from the physical standby database instead of the production database, relieving the load on the production database *ORACLE DATABASE 10G WITH DATA GUARDLogical standby database provide these advantages:A logical standby database can be used for other business purposes in addition to disaster recovery. Users can access a logical standby database for queries and reporting purposes.Enable rolling database upgrades of the production database *ORACLE DATABASE 10G WITH DATA GUARD*ORACLE DATABASE 10G WITH RAC AND DATA GUARD – MAARAC and Data Guard provide the basis of Oracle Database 10g – Maximum Availability Architecture (MAA). Symmetric sites also enable processes and procedures to be kept the same between sites, making operational tasks easier to maintain and execute.*ORACLE DATABASE 10G WITH RAC AND DATA GUARD – MAA*ORACLE DATABASE 10G WITH STREAMSOracle Database 10g with Streams provides granularity and control over what is replicated and how it is replicated. It supports bidirectional replication, data transformations, custom apply functions, and heterogeneous platformsIt supports different character sets between the primary database and its replicas.*ORACLE DATABASE 10G WITH STREAMS*DETERMINING YOUR HIGH AVAILABILITY REQUIREMENTS Analysis Framework for Determining High Availability RequirementsBusiness Impact AnalysisCost of DowntimeRecovery Time Objective (RPO)Recovery Point Objective (RTO)*DETERMINING YOUR HIGH AVAILABILITY REQUIREMENTSHigh Availability Architecture RequirementsService level agreements (SLAs) can categorize businesses into several high availability tiers:Tier 1 business processes have maximum business impact. They have the most stringent high availability requirements, with RTO and RPO close to zero.Tier 2 business processes can have slightly relaxed high availability and RTO/RPO requirements. Tier 3 business processes may be related to internal development and quality assurance processes. *DETERMINING YOUR HIGH AVAILABILITY REQUIREMENTSPlanning and Implementing a Highly Available Enterprise*ORACLE HIGH AVAILABILITY SOLUTIONS FOR UNPLANNED DOWNTIMEOutage TypeOracle SolutionComputer failuresFast-Start Fault RecoveryRACData Guard Oracle StreamsStorage failuresASMRMAN with flash recovery areaData GuardOracle StreamsHuman errorsOracle security featuresOracle Flashback technologyLogMiner*ORACLE HIGH AVAILABILITY SOLUTIONS FOR UNPLANNED DOWNTIMEOutage TypeOracle SolutionData corruptionHARDRMAN with flash recovery areaData GuardOracle StreamsSite failuresRMANData GuardOracle Streams*ORACLE HIGH AVAILABILITY SOLUTIONS FOR PLANNED DOWNTIMEOutage TypeOracle SolutionSystem changes – Dynamic Resource Provisioning, Rolling UpgradesOracle Database 10gRACData GuardMAAOracle StreamsData changes - Online Reorganization and RedefinitionOracle Database 10gRACData GuardMAAOracle Streams**