Which two statements are true about the compressed backups in RMAN? (Choose two.)
A.
Compressed backups can only be taken on the tape drives.
B.
The binary compression creates some performance overhead during backup operation.
C.
The ZLIB compression algorithm can be used only if the COMPATIBLE initialization
parameter is set to 11.1.0.
D.
The media manager compression for the tape drive should be enabled for taking
compressed backups on the tape.
The Answer is B and C.
https://docs.oracle.com/cd/B28359_01/backup.111/b28270/rcmconfa.htm
Configuring the Backup Compression Algorithm
RMAN supports binary compression of backup sets. The supported algorithms are BZIP2 (default) and ZLIB. The BZIP2 algorithm is optimized for maximum compression, whereas the ZLIB algorithm is optimized for CPU efficiency. BZIP2 consumes more CPU resource than ZLIB, but will usually produce more compact backups. The COMPATIBLE initialization parameter must be set to 11.0.0 or higher for ZLIB compression, which requires the Oracle Advanced Compression option.
No,
C is incorrect:
“The ZLIB compression algorithm can be used ONLY if the compatible initialization
parameter is set to 11.1.0.”
It’s false, the COMPATIBLE initialization parameter must be set to 11.0.0 or higher not ONLY 11.1.0…
I agree with Tommy on this one.
Answer D is also correct although it could be worded slightly better.
See
http://oracle.su/docs/11g/backup.112/e10643/rcmsynta007.htm#CHDCFGEI
and look for the text …..
COMPRESSED
RMAN applies a binary compression algorithm as it writes data to backup sets. This compression is similar to the compression provided by many media manager vendors. When backing up to a locally attached tape device, compression provided by the media management vendor is usually preferable to the binary compression provided by BACKUP AS COMPRESSED BACKUPSET. Therefore, use uncompressed backup sets and turn on the compression provided by the media management vendor when backing up to locally attached tape devices. You should not use RMAN binary compression and media manager compression together.