Ensuring High Availability for
Critical Systems and Applications
Using SharePlex™ to Ensure Your Oracle Databases Are Always Up and Running
Bill Brunt, Product Manager, Dell Software
Abstract
Keeping business systems and applications up and running requires high availability of the Oracle databases they depend upon. This technical brief explains how SharePlex™ can help organizations ensure high availability of their Oracle databases to improve overall system availability.
Introduction
What is high availability?
High availability means different things to different organizations.
Some companies measure the response time in a given application. If it is within a certain threshold, the system is considered available. Other organizations continually sample transaction or network throughputs to determine whether the system is considered available.
Application high availability requires Oracle high availability Because an Oracle database is often an integral part of a business application, any availability problems with the
database immediately impact the business application using the database. Therefore, for an application to be highly available, the underlying Oracle databases must also be highly available.
The availability of an Oracle database is affected primarily by three factors:
• Planned system outages
• Unplanned system outages
• High system load
Fortunately, you can reduce planned and unplanned system outages and control high system load. This paper explains how SharePlex can ensure Oracle high availability to help
2
SharePlex
immediately
replicates any
change in data on
the source to the
target, so the target
database is always in
sync, with no lag in
data availability.
Reducing planned Oracle outages An Oracle database requires numerous periodic maintenance tasks that either require a complete database outage or provide very limited system availability.
These tasks are typically performed on a scheduled maintenance run, which may be daily, weekly, monthly, or once every few years, depending on the nature of the task.
These periodic maintenance tasks include:
• Data warehousing using resource-intensive extract transform load (ETL) software
• Periodic reports
• System backups
• Storage tune-ups, such as adding or removing indexes, reorganizations, or collecting statistics
• Hardware changes
• Software changes, such as OS patches and database upgrades
• Migrations (moving an Oracle database from one operating system platform to another)
Traditionally, IT administrators scheduled these tasks during maintenance time windows outside of normal business hours. However, with the rapid globalization of business operations and internet access, the maintenance windows are getting smaller and smaller.
SharePlex for Oracle databases
Fortunately, SharePlex can help eliminate planned Oracle outages altogether.
The leading database replication solution, SharePlex supports high availability, disaster recovery, reporting, data movement, and application integration, all with zero to minimal impact on Oracle systems. SharePlex provides data compare and repair, in-flight data integrity, plus monitoring and alerting functionalities.
SharePlex ensures continuous, uninterrupted business flow while meeting your database operational goals by providing a real-time copy of production data without degrading your OLTP system’s performance and availability. The data is replicated from one database server to another database server, and replication runs continuously, with no scheduling required. SharePlex immediately replicates any change in data on the source to the target, so the target database is always in sync, with no lag in data availability. SharePlex employs a streaming process outside of the database instance. It creates a small footprint for minimal impact on database performance and network capacity.
Eliminating planned outages for ETL and reporting
SharePlex can help you eliminate planned outages for data warehousing using ETL software and for periodic reporting. Begin by adding a secondary Oracle database
Operational reporting/
Archiving/Data warehousing
Data distribution/
Distributed processing Centralized reporting (Consolidation)
Data integration
Structured / Unstructured Oracle
Cascading using intermediary systems High availability/
Disaster recovery
9i/10g/11g 11g/12c
Migrations, patches & upgrades
Active-Active/Load balancing Change tracking
Figure 1. Use SharePlex to ensure business continuity while meeting your database operational goals.
SharePlex can
help you eliminate
planned outages for
data warehousing
using ETL software
and for periodic
reporting.
to your network. This database can be bigger or smaller than the primary Oracle database; it can even be on different hardware or a different operating system platform, or run a different Oracle version (like Oracle Standard Edition) to save you licensing and maintenance costs.
SharePlex efficiently replicates data needed for ETL and reporting processes from your large, mission-critical systems and stages it into to the new secondary Oracle system in real time. ETL processes or reports can be run from the secondary system at any time without impacting performance, eliminating the need for planned outages of the primary Oracle database.
If there is a structural difference between primary and secondary systems, you should use SharePlex’s real-time transformation capabilities to change the SQL before it is applied to the secondary system.
Eliminating planned outages for system backups and storage tune-ups
To eliminate planned outages for system backups and storage tune-ups, add an identical secondary Oracle database to your environment. SharePlex efficiently replicates the primary Oracle database to the secondary system in real time, without impacting database performance or requiring large bandwidth. System backups can then be performed from the up-to-date secondary system, eliminating the need for downtime on your primary system.
Storage-related tasks, such as index creation, statistics gathering, and reorganizations, can also be performed on the secondary system. Once these tasks have been performed on the secondary system, use SharePlex to automatically and seamlessly switch the roles of the primary and secondary systems in seconds.
Eliminating planned outages for hardware and software changes and migrations
To eliminate planned outages for hardware and software changes and for migrations, create a secondary server that has all the software and hardware changes in place. Then have SharePlex perform a bidirectional replication between the primary and secondary systems. SharePlex is flexible enough to go between most Oracle versions and platforms (this may include introducing new database features such as RAC, ASM, etc.), so you don’t need to worry about whether the source and target versions and platforms match, as long as the replication target can hold all the object types that you are replicating.
Once the primary and secondary systems are in sync and the appropriate outage window is available, simply point your applications and users, in stages, over to the new system, and it will go live.
Regardless of the amount of testing performed, changes to the live system are never without issues, some minor, some Source
Export queue
Capture queue
Postqueue SQL
Target Cloud target
Export Import
Capture Read
Post Post
Redo/archive logs
Figure 2. The SharePlex data replication process
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more severe. Should a problem occur with the new system after going live, you can always switch back to the old system, since it has been updated by SharePlex.
This strategy has a much lower risk and involves less downtime than performing upgrades directly to the primary server.
Reducing unplanned Oracle outages Unplanned outages are caused by various forms of system failure, from simple software or hardware failures to disasters that destroy complete infrastructure, such as fires, floods, hurricanes, tornados, or terrorism.
Business continuity planning for such events is critical to risk mitigation and ultimately to the survival of the business.
Disaster recovery strategies and tools Oracle servers can be made resilient to simple unplanned server outages using built-in Oracle technology such as Real Application Cluster (RAC). However, RAC provides continuity only in cases in which the server that is processing the data fails; it does not protect against permanent storage failures. Moreover, it works only in a very small geographic range, limiting its usefulness for large- scale disaster recovery.
Many third-party disaster recovery solutions are inclusive of hardware and software. For instance, some disc vendors provide mirroring through a LAN, but that strategy, of course, has limitations related to both distance and bandwidth.
Oracle provides a solution called
Physical DataGuard, but it has limitations, including problems with bandwidth.
Using SharePlex for disaster recovery SharePlex provides a flexible, low-impact solution for disaster recovery. SharePlex replication is asynchronous and only replicates application changes to the database; therefore, SharePlex has a much smaller bandwidth requirement than other solutions. Physical distance is also not a limitation for SharePlex; many customers are using replication through their WANs across continents.
Using SharePlex to address high system loads
The amount of data captured and accessed by organizations to drive business decisions is increasing dramatically. Businesses need the most current information from their servers for operational decision-making, billing, inventory control, and so on. This up- to-the-minute information is vital to the business, but access to this transactional data comes at a cost.
Real-time reporting and real-time data requirements add overhead to already overloaded transactional systems. To support the need for access to up-to- the-minute data, organizations need a solution to lessen the strain on database systems while ensuring valuable data is always available. SharePlex is the only low-impact, real-time reporting solution that creates a secondary instance of the transactional data to offload reporting;
SharePlex reduces the strain on your production system immensely.
Conclusion
With SharePlex, you can reduce or eliminate planned and unplanned downtime. No matter what your business needs are, you can ensure Oracle database availability, regardless of edition, and achieve system and application high availability with ease.
About the author
Bill has worked with Oracle databases since 1988, and has presented several times at Oracle Open World and its predecessor. He has worked with the SharePlex replication solution for Dell as well as a customer, helping hundreds of customers increase their system availability and deploy scalable infrastructures.
His experience with Oracle includes database administration, architecture, data warehousing, Oracle E-Business Suite and application development. Including hands on experience with replication technology like change data capture, messaging queues, block level disk writes, enterprise application integration, extract transformation and load processing.
SharePlex has
a much smaller
bandwidth
requirement than
other solutions.
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