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Oracle OCP 1Z0 053 Q688(RMAN Backup Compression)

原创 Oracle 作者:abstractcyj 时间:2016-04-04 15:13:39 0 删除 编辑
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

参考:http://blog.itpub.net/17013648/viewspace-1346728/
如果要把数据存放在带库中,则需要启用media manager compression机制

compatible参数应该是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算法为了最大化压缩,ZLIB则是为了节约CPU资源,自然, bzip2在CPU资源消耗方面就比ZLIB算法要多。

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