Both RTO and RPO are
essential elements of business continuity, and they sound quite similar. But
their purpose is quite different.
What is RTO?
So, what does RTO
mean? BS 25999-2, a leading business continuity standard, defines
RTO as “…target time set for resumption of product, service or activity
delivery after an incident”.
This actually means
that RTO is crucial when implementing business continuity in a company –
calculating how quickly you need to recover will determine what kind of
preparations are necessary. For example, if RTO is 2 hours, then you need to
invest quite a lot of money in a disaster recovery center, telecommunications,
automated systems, etc. – because you want to be able to achieve full recovery
in only 2 hours. However, if your RTO is 2 weeks, then the required investment
will be much lower because you will have enough time to acquire resources after
an incident has occurred.
RTO is determined
during the business impact analysis (BIA), and the preparations are defined in
the business continuity strategy.
What is RPO?
Recovery point objective is a totally
different thing – according to Wikipedia, RPO is “… the maximum tolerable
period in which data might be lost”. As this is quite difficult to grasp right
away, I like to use this example instead – ask yourself how much data you can
afford to lose? If you are filling in a database with various kinds of
information, is it tolerable to lose 1 hour of work, 2 hours or maybe 2 days?
If you are writing a lengthy document, can you afford to lose 4 hours of your
work, the whole day or perhaps you could bear if you lost your whole week’s
job?
This number of hours or days is the
RPO. Recovery Point Objective is crucial for determining one element of
business continuity strategy – the frequency of backup. If your RPO is 4 hours,
then you need to perform backup at least every 4 hours; every 24 hours would
put you in a big danger, but if you do it every 1 hour, it might cost you too
much.
So, what’s the
difference between RTO and RPO?
The difference is in the purpose – RTO
has a broader purpose because it sets the boundaries for your whole business
continuity management, while RPO is focused solely on the issue of backup
frequency. They are not directly related – you could have RTO of 24 hours and
RPO of 1 hour, or RTO of 2 hours and RPO of 12 hours.
But let me emphasize what is even more
important: what do RTO and RPO have in common? They are both crucial for
business impact analysis and for business continuity management. Without
determining them properly, you would be just guessing – and guessing is the
best way to ensure you never recover from a disaster.
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