Explain the difference between a hot backup
and a cold backup and the benefits associated with each.
A hot
backup is basically taking a backup of the database while it is still up and
running and it must be in archive log mode.
A cold
backup is taking a backup of the database while it is shut down and does not require
being in archive log mode.
The
benefit of taking a hot backup is that the database is still available
for use
while the backup is occurring and you can recover the database to any point in
time.
The
benefit of taking a cold backup is that it is typically easier to administer
the backup and recovery process.
In addition, since you are taking cold backups the database does not require being in archive log mode and thus there will be a slight performance gain as the database is not cutting archive logs to disk.
In addition, since you are taking cold backups the database does not require being in archive log mode and thus there will be a slight performance gain as the database is not cutting archive logs to disk.
You
have just had to restore from backup and do not have any control files. How would
you go about bringing up this database?
I would
create a text based backup control file, stipulating where on disk all the data
files where and then issue the recover command with the using backup control
file clause.
Explain
the difference between a data block, an extent and a segment.
A data
block is the smallest unit of logical storage for a database object. As objects
grow they take chunks of additional storage that are composed of contiguous
data blocks.
These
groupings of contiguous data blocks are called extents. All the extents that an
object takes when grouped together are considered the segment of the database
object.
Explain
the difference between ARCHIVELOG mode and NOARCHIVELOG mode and the benefits
and disadvantages to each.
ARCHIVELOG
mode is a mode that you can put the database in for creating a backup of all
transactions that have occurred in the database so that you can recover to any
point in time.
NOARCHIVELOG
mode is basically the absence of ARCHIVELOG mode and has the disadvantage of
not being able to recover to any point in time.
NOARCHIVELOG
mode does have the advantage of not having to write transactions to an archive
log and thus increases the performance of the database slightly.
Give
the stages of instance startup to a usable state where normal users may access it.
STARTUP NOMOUNT - Instance startup
ALTER DATABASE MOUNT - The database is
mounted
ALTER DATABASE OPEN - The database is
opened
Explain
the difference between $ORACLE_HOME and $ORACLE_BASE.
ORACLE_BASE
is the root directory for oracle. ORACLE_HOME located beneath ORACLE_BASE is where
the oracle products reside.