A) Recovery Point Objective(RPO)
A recovery point objective (RPO) is the maximum length of time permitted that data can be restored from, which may or may not mean data loss.
RPO concerns with data. It is the amount of data you are willing to lose when the failure occurs in your database system. Usually people define data loss in terms of time, so possible values can be 5 seconds of data loss, 2 hours of data loss etc.
Remember that each standby database has its own set of attributes and parameters. It means you can mix zero data loss standby databases with minimal data loss standby databases in the same Data Guard configuration.
If you have decided that you want to implement zero data loss strategy, then you should really focus on Networks and Data Loss.
B) Recovery Time Objective (RTO)
The recovery time objective (RTO) is the targeted duration of time between the event of failure and the point where operations resume.
RTO is defined as how fast you can get back up and running (whereas RPO is concerned with data loss)
So with your RPO strategy you lost say only about 6 seconds of data as you committed to your client but with RTO you need to formulate how fast clients can connect back to the database system after the data loss has occurred.
RTO Vs RPO
The main difference is in their purposes – being focused on time, RTO is focused on downtime of services, applications, and processes, helping define resources to be allocated to business continuity; while RPO, being focused on amount of data, has as its sole purpose to define backup frequency.
Another important difference is in the purpose behind the two. RTO places a time frame on viable strategic options that enable an organization to resume business without the use of data, while RPO is a measurement of the amount of time that data can be permitted to be lost, and is not a measure of how much data might be lost.
Another relevant difference is that, in relation to the moment of the disruptive incident, RTO looks forward in time (i.e., the amount of time you need to resume operations), while RPO looks back (i.e., the amount of time or data you are willing to lose).
What does RTO mean in disaster recovery solutions?
Recovery Time Objective (RTO) is the duration of time and a service level within which a business process must be restored after a disaster in order to avoid unacceptable consequences associated with a break in continuity. In other words, the RTO is the answer to the question: "How much time did it take to recover after notification of business process disruption?"
RPO designates the variable amount of data that will be lost or will have to be re-entered during network downtime. RTO designates the amount of "real time" that can pass before the disruption begins to seriously and unacceptably impede the flow of normal business operations.
