All language subtitles for [SubtitleTools.com] RMAN Backup Maintenance - Learning Oracle 12c [Video]

In this lesson, we're going
to look at RMAN maintenance--

so how to do maintenance
on RMAN backups.

So we've said that RMAN
is the preferred way

of doing backup and recoveries
on an Oracle database.

However, there are
some maintenance tasks

that have to be accomplished
because if we've set up

our database to have
weekly backups, let's say,

those old backups
need to be removed--

and archive logs, as well.

So the archive logs are not
needed past a certain point

because our backups are newer
than those archive logs.

So all of that goes into
maintenance for a database.

We primarily gain information
about the database

and its backup status using
two commands in RMAN--

list and report.

So let's go into RMAN--

connect target-- and do a
list backup of database.

So this command is
going to give us

information about
the backups that

have occurred in our database.

So it may give us things
like the type of backups--

here it says full.

It tells us the piece name, so
exactly where the backup file

is, when it completed, when it's
elapsed time was or how long,

what type--

was it disk or to tape.

And if we look a
little further, we

can see type INCR
for incremental.

And it's an incremental
LV for level--

0-- the size, the data
files that were involved.

Here is an incremental
level 1 as well.

So that gives us the information
about the backups that

have occurred in our database.

So list backup of database.

One of the most important
commands that we could use

is to find out whether
or not RMAN thinks

that there are any files
in the database that

do need to be backed up.

So this is really
important in situations

where sometimes
if a backup fails,

say for lack of space,
what exactly got backed up,

how much was completed, and
what does RMAN think still

needs to be done.

So a report need
backup command--

now that will tell
us whether or not

RMAN thinks any data files
need to be backed up.

And notice that it comes back
with no information here,

so it's null information.

So that tells us that there are
no data files in our database

that need to be backed up.

Well, what if we
were to add one?

So let's go in here and
create a tablespace.

So now we have a
tablespace named test10.

It has a data file
associated with it.

So let's run that command again.

And notice that as
soon as we create

that tablespace it now says that
datafile needs to be backed up.

So RMAN is smart enough
to go out and know

the state of the database.

Now, another major command
for maintaining our space--

because we always have a
limited amount of space

that we could use for
the fast recovery area--

is to do report obsolete.

So report obsolete
is going to give us

a list of all of the backups and
archive logs and image copies

or anything that we have
in the flash recovery

area that is obsolete
and can be removed.

So notice here that we
have a number of files--

archive logs, backup sets--

that can be removed.

In order to remove
these, we'll use

the delete obsolete command.

So when we do delete obsolete,
the first thing it does

is come back with the
list of obsoletes--

this is what we just saw with
the report obsolete command.

Do you really want to
delete the above objects?

I'm going to type no here,
because oftentimes if we script

our backup, we don't want
the interruption of it

asking a question.

If we tell it to delete
we want it to delete.

That's the kind of
commands we would put

in an automatic scheduled job.

So we would use delete
noprompt obsolete.

And then it will go
ahead and delete those

without asking us whether
or not we want to do it.

Notice that we have
deleted archive

logs, deleted backup
piece, so on, and so forth.

So now if we say
report obsolete again,

no obsolete backups were found.

And finally the
crosscheck command.

It's very important
when you do RMAN backups

that you use these commands
to do your maintenance

to remove your files because if
you go out onto the file system

itself, and you delete
the backup pieces

that you think are old enough
or delete archive logs,

then RMAN doesn't
know about those

because we didn't interact
with RMAN when we removed them.

And the way that RMAN
discovers what is missing

and can update its catalog
is the crosscheck command.

So he would say crosscheck
backup of database.

And then it gives a list of the
backup pieces that it found.

If there are any
that it expected

to be there that
weren't there, then it

will say that they are expired,
and we can go and do cleanup

from there using
delete obsolete.