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Discover what's behind Oracle database backup and recovery!
Solve your database recovery problems with our Oracle RMAN backup and recovery procedure.
The Linkedin password hack and Oracle databases
Seen on 09.06.2012.
What has the recent Linkedin password hack to do with Oracle databases?
How can we check if an Oracle database is vulnerable to the same type of hack and more important, protect it?
Enjoy reading this well written article by Arup Nanda!
Oracle food for thought, for free!
Seen on 13.04.2012.
Do you want to spend the long Easter weekend differently? Learn something new about Oracle or refresh your knowledge?
Here's a time limited offer to download Thomas Kyte's ebook "Expert Oracle Database Architecture, 2nd Edition" for free!
This is a legal download, you can choose between pdf, epub and mobi formats.
Overview Standby Solutions
1. Oracle Active Data Guard
Gives you a standby solution which improves quality of service for critical business transactions.
Offload long-running tasks like ad-hoc queries, report generation, and backups to an up-to-date replica of your production database.
Keep the production database active for business critical transactions while offloading tasks to the active data guard standby.
Data is always up to date for ad-hoc queries.
Oracle Active Data Guard enables a physical standby database to be open for read-only access - for reporting, simple or complex queries, sorting, web-based access, etc. while changes from the production database are being applied to it.
All queries reading from the physical replica execute in real-time, and return current results.
This means any operation that requires up-to-date read-only access can be offloaded to the replica, enhancing and protecting the performance of the production database.
This capability makes it possible for Active Data Guard to be deployed for a wide variety of business applications:
Recovery Manager (RMAN) benefits with Oracle Active Data Guard:
RMAN block-change tracking on a physical standby database. This feature allows very fast incremental backups on the standby database.
Requires Oracle Enterprise Edition. Oracle Active Data Guard must be licensed separately.
2. Oracle Data Guard
The most popular use for Oracle Data guard is to synchronize the physical database with its production counter part for data protection and high availability.
Data Guard operates on a simple principle: ship redo, and then apply redo.
Redo includes all of the information needed by the Oracle Database to recover a database transaction.
A production database, referred to as the primary database, transmits redo to one or more independent replicas referred to as standby databases.
Data Guard standby databases are in a continuous state of recovery, validating and applying redo to maintain synchronization with the primary database.
Data Guard will also automatically resynchronize a standby database that becomes temporarily disconnected from its primary database because of a network or standby outage.
The Oracle data guard standby database is normally not open for read-only queries. To use it for read-only queries, the database administrator has to stop the redo apply and open the database for reporting purposes.
RMAN benefits with Oracle Data Guard:
RMAN database backups can be offloaded in a Data Guard environment the physical standby database. However, RMAN block-change tracking on a physical standby database requires an Oracle Active Data Guard license.
Requires only Oracle Enterprise Edition, Data Guard is included.
3. Dbvisit standby
Oracle disaster recovery software
Dbvisit standby is trusted in over 50 countries to protect against hardware and logical failures, natural disasters, human error and outages.
It is the alternative to Oracle Data Guard enabling you to cost-effectively protect your critical data infrastructure and get more out of your existing investment in Oracle database, Standard Edition and Standard Edition One software.
Works with any Oracle database edition.
4. Data Guard versus Remote Mirroring
What is the advantage of Data Guard?
Data Guard transmits only redo data - the information needed to recover a database transaction - to synchronize a standby database with its primary.
Data Guard also prevents the primary from propagating corruption by performing Oracle validation before applying changes to a standby database.
Before Data Guard became available, companies would use storage or host-based remote mirroring to maintain a synchronized copy of their Oracle database files.
Unfortunately, remote mirroring does not have any knowledge of an Oracle transaction; thus it cannot distinguish between redo, undo, data block changes, or control file writes.
This requires remote mirroring to transmit every write to every file, generating 7 times the network volume and 27 times more network I/O operations than Data Guard.
Remote mirroring is also unable to perform Oracle validation, making it impossible to provide the same level of protection as Data Guard.
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