Monday, March 07, 2016

Zero Data Loss Recovery Appliance - Basics

Oracle released Zero Data Loss Recovery Appliance in 2014. The Recovery Appliance was designed to ensure efficient and consistent Oracle Database Backups with a very key focus on Recovery.
I am going to write a series of blogs starting with this one to discuss the fundamental architecture of the Recovery Appliance and discuss the business case as well as deployment and operational strategies around the Recovery Appliance.
So Lets start with why an Appliance. Oracle has had a very interesting strategy start from way before the sun Acquisition. The Exadata was a prime example of a Database Machine that was optimized for Database Workloads. The Engineered Systems Family has since grown to include the smaller Oracle Database Appliance to the currently newest member of the family Zero Data loss recovery Appliance.

Now Lets Start with the Basics . The Recovery Appliance as the name suggests is an Appliance built to solve Data Protection gaps that most customers face , when trying to ensure their critical data that most often resides in the Oracle Database. So why recovery appliance and why now. Over the years Data storage has continued to grow and so does the amount of data stored in databases, where once a couple of GB’s of data was a big deal, today organizations are dealing with Petabytes of Database Storage. Database’s backups are getting harder and harder to manage and modern Backup Appliances have a focus on getting more out of the storage rather than provide a way to ensure recoverability and don’t have a good enough method to ensure that backups are valid. The Recovery Appliance is designed to solve these challenges and give customer an autopilot for their backups.
The name Recovery appliance suggests how much emphasis was put forward in ensuring recoverability of the database, and hence there were controls put in place to ensure everything is validated not just once , but on a regular basis, with extensive reporting made available.Backups are a very important part of every enterprise and the Recovery Appliance brings the ability to perform an incremental forever backup strategy. The incremental forever strategy as the name suggests provides for one full backup (Level 0 ) followed by subsequent incrementals (Level 1 ) Backups. This in conjunction with Protection Policies that ensure a recovery window is maintained , thus providing the autopilot that ensures backups are successful with very little overhead on the machine that is taking the backup. This is done by offloading the de-duplication and compression activities to the Recovery Appliance.
So far i’ve used terminologies like Protection Policies , De-duplication , compression etc. While these terminologies are common in the backup space , too often people have a hard time making the connection. So lets start by a brief definition of each term
Full Backups
When a Complete Backup of the database is taken, This is called a Full Backup and in a traditional environment, this can be done daily or weekly , depending on the backup strategy . Traditional Backup appliances rely on these full to provide De-duplication capabilities. Full backup require a lot of overhead since all blocks have to be read from the I/O subsystem and processed by database host.
Incremental Backups
Incremental backups as the name suggests is the ability to take backups of data blocks that have changed since the previous backups. The Oracle Backup and Recovery Users Guide is the best place to understand the incremental backup strategy and how that can be employed in terms of a backup strategy.
De-duplication
De-duplication is a technique to eliminate duplicate copies of repeating data. This technique is typically employed with flat files or text based data since you can find a better repeating . Incremental Backups are a poor source to de-dup since there is not much data that is repeating and due to the unique structure of the Oracle block , it makes it hard to get a lot of de-duplication.
Compression
Compression is act of shrinking data and Oracle provides various methods of compressing data within the database and with the rman backup process itself.
In Part 2 of this Blog post i will talk about some of the terminologies likes protection policies and incremental forever strategy as well as dicuss the architecture of the Recovery Appliance.


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