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.
@24707 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.
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