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  • rman压缩备份题目

    ocp 053

    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 in itialization 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 

    答案解析:

    A错,也可以备份在disk上。

    C错, only if the  COMPATIBLE in itialization parameter is set to 11.1.0,应该是11.0.0或者以上

    sys@TEST0221> select ALGORITHM_NAME,ALGORITHM_COMPATIBILITY,ALGORITHM_DESCRIPTION from v$rman_compression_algorithm

      2  /

    ALGORITHM_NAME                                                   ALGORITHM_COMPATIB ALGORITHM_DESCRIPTION

    ---------------------------------------------------------------- ------------------ ----------------------------------------------------------------

    BZIP2                                                            9.2.0.0.0          good compression ratio

    BASIC                                                            9.2.0.0.0          good compression ratio

    LOW                                                              11.2.0.0.0         maximum possible compression speed

    ZLIB                                                             11.0.0.0.0         balance between speed and compression ratio

    MEDIUM                                                           11.0.0.0.0         balance between speed and compression ratio

    HIGH                                                             11.2.0.0.0         maximum possible compression ratio

    6 rows selected.

    本机测试:竟然没有ZLIB

    16:23:29 SYS@db252>col ALGORITHM_NAME for a40
    16:23:45 SYS@db252>col ALGORITHM_NAME for a10
    16:23:57 SYS@db252>col ,ALGORITHM_DESCRIPTION for a40
    16:24:12 SYS@db252>select ALGORITHM_NAME,ALGORITHM_COMPATIBILITY,ALGORITHM_DESCRIPTION from v$rman_compression_algorithm;

    ALGORITHM_ ALGORITHM_COMPATIB ALGORITHM_DESCRIPTION
    ---------- ------------------ ----------------------------------------------------------------
    BASIC 9.2.0.0.0 good compression ratio
    LOW 11.2.0.0.0 maximum possible compression speed
    MEDIUM 11.0.0.0.0 balance between speed and compression ratio
    HIGH 11.2.0.0.0 maximum possible compression ratio

    Elapsed: 00:00:00.02
    16:24:13 SYS@db252>

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  • 原文地址:https://www.cnblogs.com/gispf/p/3793018.html
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