In regards to the different modes, they are documented here:
But in a nutshell, maximum performance mode is the mode with the least
impact on the primary database, but also the one offering the least
protection. In this mode, the standby runs asynchronously, and data is
committed on the standby whenever it arrives there.
Maximum protection on the other hand is the opposite and will shut down the
primary if it can't reach the standby, to ensure that no data is lost. In
this mode, the standby runs synchronously and the primary won't be able to
commit the transaction until it has been committed on at least one standby
as well. Normally you don't want to run this mode without having at least
two standby databases.
Maximum availability runs in the same mode as max protection by default,
but will automatically fall back to max performance if it can't reach the
Aside from force logging (which is a must with Data Guard as Norman has
already explained), the impact that synchronous commit has shouldn't be
disregarded, as it vastly depends on your network infrastructure
(particularly latency if e.g. the primary and standby are in different data
centers) and can easily cripple your primary database's throughput.
Which mode to choose is usually decided by the business requirement that
drives the need for a standby - be it for example with a primary focus to
avoid data loss as much as possible, or to just have a failover database in
place, in case the primary fails. It depends.
In extreme cases, you can also leave the primary database in "specific
forced logging" mode. Meaning that you have the OLTP-focused data in force
logging tablespaces, but not the batch-focused tablespaces. But you will
then have to synchronize the standby each morning, using an incremental
backup. I am assuming if you are using nologging, that you are already
triggering an incremental after the batch completes. But, needless to say,
a setup like this can be dangerous and needs greater care and particularly
education, if multiple team members are working on said database. All it
takes is for one guy to create a tablespace without force logging enabled
on it, and you're up for data loss (at some random point months or years
later down the road).
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