ORACLE DATABASE HIGH AVAILABILITY 1

OUTLINE I. Overview Of High Availability II. Oracle Database High Availability Architecture III. Determining Your High Availability Requirements 2

O VERVIEW O F H IGH A VAILABILITY What 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. 3

O VERVIEW O F H IGH A VAILABILITY  Recoverability: there may have many choices in recovering from a failure. Hence, the most appropriate action is also to satisfy business requirements most  Timely 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. 4

O VERVIEW O F H IGH A VAILABILITY Importance Of High Availability Support enterprises to gain their competitive advantages by providing capability of continuously accessing to critical business data. Much downtime (surpass the threshold) can cause  Direct cost: lost productivity, lost revenue.  Indirect cost: damaged customer relationships, bad publicity, and lawsuits. 5

O VERVIEW O F H IGH A VAILABILITY Causes Of Downtime  Unplanned:  Computer failure  Storage failure  Human error  Data corruption  Site failure  Planned:  System changes  Data changes 6

O VERVIEW O F H IGH A VAILABILITY Causes Of Downtime  Unplanned:  Computer failure A 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 7

O VERVIEW O F H IGH A VAILABILITY Causes Of Downtime  Unplanned:  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 8

O VERVIEW O F H IGH A VAILABILITY Causes Of Downtime  Unplanned:  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 9

O VERVIEW O F H IGH A VAILABILITY Causes Of Downtime  Unplanned:  Site failure A 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 level Example: Site-wide network failure Natural disaster Terrorist or malicious attack on operations or the site 10

O VERVIEW O F H IGH A VAILABILITY Causes Of Downtime  Planned:  System changes Planned 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 11

O VERVIEW O F H IGH A VAILABILITY Causes Of Downtime  Planned:  Data changes Planned 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 12

O RACLE D ATABASE H IGH A VAILABILITY A RCHITECTURE Oracle Database 10g  Oracle Flashback Technology  Automatic Storage Management  Recovery Manager  Flash Recovery Area  Online Reorganization and Redefinition Oracle Database 10g with RAC Oracle Database 10g with Data Guard Oracle Database 10g with RAC and Data Guard – MAA Oracle Database 10g with Streams 13

S TANDARD O RACLE D ATABASE 10 G HIGH AVAILABILITY  Oracle 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 Query  Oracle Flashback Versions Query  Oracle Flashback Transaction Query  Oracle Flashback Table  Oracle Flashback Drop  Oracle Flashback Database  Oracle Flashback Restore Points 14

S TANDARD O RACLE D ATABASE 10 G HIGH AVAILABILITY  Automatic 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 disks  Instead 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. 15

S TANDARD O RACLE D ATABASE 10 G HIGH AVAILABILITY  Automatic Storage Management (ASM)  With ASM mirroring, an additional level of data protection can be provided with the use of failures groups. 16

S TANDARD O RACLE D ATABASE 10 G HIGH AVAILABILITY Mirroring OptionDescription 2-way mirroring Each extent has 1 mirrored copy. 3-way mirroring Each extent has 2 mirrored copies. Unprotected ASM provides no mirroring. Used when mirroring is provided by the disk subsystem itself. ASM Mirroring Options 17

S TANDARD O RACLE D ATABASE 10 G HIGH AVAILABILITY Mirroring Options for Each Disk Group Type Disk Group Type Supported Mirroring Levels Default Mirroring Level Normal redundancy 2-way 3-way Unprotected (none) 2-way High redundancy 3-way External redundancy Unprotected (none)Unprotected 18

S TANDARD O RACLE D ATABASE 10 G HIGH AVAILABILITY  Recovery Manager Recovery 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 19

S TANDARD O RACLE D ATABASE 10 G HIGH AVAILABILITY  Flash Recovery Area  The 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. 20

S TANDARD O RACLE D ATABASE 10 G HIGH AVAILABILITY  Online Reorganization and Redefinition  One 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 online  Online move of a partitioned table. 21

O RACLE D ATABASE 10 G WITH RAC  Oracle Database 10g with RAC architecture uses Real Application Clusters and is an inherently high availability system 22

O RACLE D ATABASE 10 G WITH RAC  This 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 23

O RACLE D ATABASE 10 G WITH D ATA G UARD  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 database Logical standby database 24

O RACLE D ATABASE 10 G WITH D ATA G UARD Physical standby database provide these advantages:  Protection from user errors and logical corruption  Protection from disasters and site failures if located remotely  Standby database can diverge for reporting or testing purposes and resynchronize with its primary database once complete  Backups can be taken from the physical standby database instead of the production database, relieving the load on the production database 25

O RACLE D ATABASE 10 G WITH D ATA G UARD Logical 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 26

O RACLE D ATABASE 10 G WITH D ATA G UARD 27

O RACLE D ATABASE 10 G WITH RAC AND D ATA G UARD – MAA RAC 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. 28

O RACLE D ATABASE 10 G WITH RAC AND D ATA G UARD – MAA 29

O RACLE D ATABASE 10 G WITH S TREAMS Oracle 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 platforms It supports different character sets between the primary database and its replicas. 30

O RACLE D ATABASE 10 G WITH S TREAMS 31

D ETERMINING Y OUR H IGH A VAILABILITY R EQUIREMENTS Analysis Framework for Determining High Availability Requirements Business Impact Analysis Cost of Downtime Recovery Time Objective (RPO) Recovery Point Objective (RTO) 32

D ETERMINING Y OUR H IGH A VAILABILITY R EQUIREMENTS High Availability Architecture Requirements Service 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. 33

D ETERMINING Y OUR H IGH A VAILABILITY R EQUIREMENTS Planning and Implementing a Highly Available Enterprise 34

O RACLE H IGH A VAILABILITY S OLUTIONS FOR U NPLANNED D OWNTIME Outage TypeOracle Solution Computer failuresFast-Start Fault Recovery RAC Data Guard Oracle Streams Storage failuresASM RMAN with flash recovery area Data Guard Oracle Streams Human errorsOracle security features Oracle Flashback technology LogMiner 35

O RACLE H IGH A VAILABILITY S OLUTIONS FOR U NPLANNED D OWNTIME Outage TypeOracle Solution Data corruptionHARD RMAN with flash recovery area Data Guard Oracle Streams Site failuresRMAN Data Guard Oracle Streams 36

O RACLE H IGH A VAILABILITY S OLUTIONS FOR PLANNED D OWNTIME Outage TypeOracle Solution System changes – Dynamic Resource Provisioning, Rolling Upgrades Oracle Database 10g RAC Data Guard MAA Oracle Streams Data changes - Online Reorganization and Redefinition Oracle Database 10g RAC Data Guard MAA Oracle Streams 37

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