Oracle OCP 1Z0 053 Q688(RMAN Backup Compression)

abstractcyj發表於2016-04-04
Oracle
688. 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.
Answer:BD

參考：http://blog.itpub.net/17013648/viewspace-1346728/
如果要把資料存放在帶庫中，則需要啟用media manager compression機制

compatible引數應該是11.0.0以上， 而不是11.1.0

The COMPATIBLE initialization parameter must be set to 11.0.0 or higher for ZLIB compression, which requires the Oracle Advanced Compression option.

另外:  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.

意思是bzip2演算法為了最大化壓縮，ZLIB則是為了節約CPU資源，自然， bzip2在CPU資源消耗方面就比ZLIB演算法要多。

來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/8520577/viewspace-2075017/，如需轉載，請註明出處，否則將追究法律責任。

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