Recovery Time Objective (RTO) refers to how long it takes to recover your data and appications in the event of system outage or data loss.
Recovery Point Objective (RPO) refers to how granular your data recovery can be. Can you go back to the very last change or is the most recent recoverable version of a file hours or even days old?
The recovery point objective (RPO) and the recovery time objective (RTO) are two very specific parameters that are closely associated with recovery. The RTO is how long you can basically go without a specific application. This is often associated with your maximum allowable or maximum tolerable outage.
The RTO is really used to dictate your use of replication or backup to tape or disk. That also dictates what you will put together for an infrastructure whether it's a high-availability cluster for seamless failover or something more modest. If your RTO is zero (I cannot go down) then you may opt to have a completely redundant infrastructure with replicated data offsite and so on. If your RTO is 48 hours or 72 hours then maybe tape backup is OK for that specific application. That's the RTO.
The RPO is slightly different. This dictates the allowable data loss -- how much data can I afford to lose? In other words, if I do a nightly backup at 7:00 p.m. and my system goes up in flames at 4:00 p.m. the following day, everything that was changed since my last backup is lost. My RPO in this particular context is the previous day's backup. If I'm a company that does online transaction processing -- American Express for example -- well maybe my RPO is down to the last, latest transaction, the latest bits of information that came in. Again, that dictates the kind of data protection solution you want in place.
So both of them, RTO and RPO, really influence the kind of redundancy or backup infrastructure you will put together. The tighter the RTO, and the tighter the RPO, the more money you will spend on your infrastructure.
Thank you. So without looking at your response, here's what I now believe to be true:
RTO is the maximum amount of time that your application can be unavailable; the maximum time the business can tolerate (stated in minutes or hours).
RPO has to do more with the amount of data recovery that a business can afford / tolerate. One business may be able to lose an hour's data; another may be able to lose NO data at all.
I think I've got it (unless I get responses to the contrary!!!)
Can i just throw a 3rd one in here? i did the Solution Design Workshop earlier in the year and the instructor mentions RTDA which is "Recover Time to Data Availability".
His explanation of this makes for interesting consideration.
If you have a 4 hour RTO so this is the SLA to have everything back online.
And you have a 30 minute RPO so this is the window for acceptable data loss.
you need to consider how long it takes to get the data from the DR location onto the server and then replay logs or make application adjustments or for any othe manual tasks that are required to get applications running. So here we come to RTDA, which is how long it takes to get the data back for the application to use to enable us to meet the RTO and RPO.
It gets forgotten and i must say until he mentioned it i hadn't considered it but now it's first on my list of questions to ask. If you have daily backups that go off-site a 4 hour RTO may not be possible if it takes 2 hours to get the media back and then 3 hours to do the restore.
The most simplest explaination is the following
Recovery Point Objective (RPO): the point in time to which the systems and data must be recovered after an outage---defines the amount of data loss that a business can handle--based on RPO minimum frequency with which a backup or replica must be made is decided---for example if RPO is 6 hrs, then backup must be made every 6hours
Recovery Time Objective (RTO): the time within which systems, apps or functions must be recovered after an outage---defines the amount of downtime a business can endure----based on RTO, DR plans are optimized---for example if RTO is 2 hrs or less we use disk drives, as they are faster than tape drives