RMAN INTERVIEW QUESTIONS AND ANSWERS
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Recovery Manager(RMAN) is an oracle
provided utility for backup restoring and recovering oracle database.
RMAN ships with the database server and doesn’t require a separate
installation. The RMAN executable is located in your ORACLE_HOME/bin
directory
In fact RMAN, is just like a Pro*C
application that translates commands to a PL/SQL interface. The PL/SQL
calls are statically linked into the oracle kernel, and does not require
the database to be opened (mapped from the ?/rdms/admin/recover.bsq file)
RMAN can do off-line and on-line database
backup. It cannot, however, write directly to the tape, but various 3rd party tools(like Veritas, Omniback(HP
Data Protector), etc ) can integrated with RMAN to handle tape library
management
2. What are the architectural components in RMAN?
RMAN executable
Server processes
Channels
Target database
Recovery catalog database (optional)
Media management layer (optional)
Backup, backup sets and backup pieces
Target database
Recovery catalog database (optional)
Media management layer (optional)
Backup, backup sets and backup pieces
3. WHY USE RMAN ?
Proper security
You are 100% sure your database has been
backed up.
Its contains detail of the backups taken etc
in its central repository
Facility for testing validity of backups also
commands like crosscheck to check the status of backup.
Faster backups and restores compared to
backups without RMAN
RMAN is the only backup tool which supports
incremental backups.
Oracle 10g has got further optimized
incremental backup which has resulted in improvement of performance during
backup and recovery time
Parallel operations are supported
Better querying facility for knowing different
details of backup
Maintains repository of backup metadata
Remembers backup set location Knows what
need to backed up
4. Which files must be backed up?
Database files(with RMAN)
Control files ( with RMAN)
Offline redolog files(with RMAN)
INIT.ORA(manually)
Password files ( manually)
5. What are channels?
A channel is an
RMAN server process started when there is a need to communicate
with an I/O device. Such as a disk or a tape. A channel is what reads and
writes RMAN backup files. It is through the allocation of channels that
govern I/O characteristics such as
Types of I/O device being read or written to, either a disk or an sbt_tape
Number of processes simultaneously
accessing an I/O device
Max size of files created on I/O devices
Max rate at which database files are
read
Max number of files open at a time
6. Why is the catalog optional?
Because RMAN manage
backup and recovery operations, it requires a place to store
necessary information about the database. RMAN always stores
this information in the target database control file. You can also store
RMAN metadata is a recovery catalog schema contained in a separate
database. The recovery catalog.
Schema must be stored in a database other
than the target database
7. What is the backup set?
A logical
group of backup files-the backup pieces- that are created when you issue
an RMAN backup command. A backup set is RMAN’s name for a collection of
files associated with a backup. A backup set is composed of one or
more backup pieces.
8. How does one
backup and restore a database using RMAN?
The biggest advantage of RMAN is that it only backup used space in the database. RMAN doesn’t put tablespaces in backup mode, saving on redo generation overhead. RMAN will re-read database blocks until it gets a consistent image of it. Look as this simple backup
9.
Where should the catalog be created?
The
recovery catalog to be used by the RMAN should be created
separate database other than the target database. The reason
been that the target database wil be shutdown while data
files are restored
10. How
many times does oracle ask before dropping a catalog?
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