Oracle-31-备份和恢复

先来看一个参数，影响数据库恢复的时间

SYS@ orcl>show parameter mttr

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
fast_start_mttr_target               integer     0

这个参数影响我们做恢复时所用的时间，如果设置了该值，数据库就会保证恢复数据的时间不会超过所设定的值（也就是说会根据数据库自己测算的写脏块的速度，调整内存脏数据写到日志文件中的频率）

下面我们看下归档日志的存放路径

SYS@ orcl>show parameter recovery

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest                string      +FLASH
db_recovery_file_dest_size           big integer 15882M
recovery_parallelism                 integer     0

查看闪回区的使用情况

SYS@ orcl>col name for a20
SYS@ orcl>col space_limit for 99999999999
SYS@ orcl>select * from v$recovery_file_dest;

NAME                  SPACE_LIMIT SPACE_USED SPACE_RECLAIMABLE NUMBER_OF_FILES
-------------------- ------------ ---------- ----------------- ---------------
+FLASH                16653484032  171966464                 0               4

Elapsed: 00:00:00.01

也可以换成MB显示

SYS@ orcl>select name,SPACE_LIMIT/1048576,SPACE_USED/1048576 from v$recovery_file_dest;

NAME                 SPACE_LIMIT/1048576 SPACE_USED/1048576
-------------------- ------------------- ------------------
+FLASH                             15882                164

Elapsed: 00:00:00.03

闪回区里面还可以存放数据库关键文件的镜像

SYS@ orcl>select * from v$controlfile;

STATUS  NAME                                               IS_ BLOCK_SIZE FILE_SIZE_BLKS
------- -------------------------------------------------- --- ---------- --------------
        +DATA/orcl/controlfile/current.260.982157551       NO       16384            594
        +FLASH/orcl/controlfile/current.256.982157551      YES      16384            594

Elapsed: 00:00:00.00

SYS@ orcl>select * from v$log;

    GROUP#    THREAD#  SEQUENCE#      BYTES  BLOCKSIZE    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIME
---------- ---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- ------------------
NEXT_CHANGE# NEXT_TIME
------------ ------------------
         1          1         10   52428800        512          2 NO  CURRENT                1110841 23-JUL-18
  2.8147E+14

         2          1          8   52428800        512          2 NO  INACTIVE               1095134 23-JUL-18
     1103706 23-JUL-18

         3          1          9   52428800        512          2 NO  INACTIVE               1103706 23-JUL-18
     1110841 23-JUL-18


Elapsed: 00:00:00.02

SYS@ orcl>select * from v$logfile;

    GROUP# STATUS  TYPE    MEMBER                                             IS_
---------- ------- ------- -------------------------------------------------- ---
         3         ONLINE  +DATA/orcl/onlinelog/group_3.263.982157555         NO
         3         ONLINE  +FLASH/orcl/onlinelog/group_3.259.982157557        YES
         2         ONLINE  +DATA/orcl/onlinelog/group_2.262.982157553         NO
         2         ONLINE  +FLASH/orcl/onlinelog/group_2.258.982157555        YES
         1         ONLINE  +DATA/orcl/onlinelog/group_1.261.982157551         NO
         1         ONLINE  +FLASH/orcl/onlinelog/group_1.257.982157553        YES

6 rows selected.

Elapsed: 00:00:00.01

SYS@ orcl>archive log list
Database log mode              No Archive Mode
Automatic archival             Disabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     8
Current log sequence           10
SYS@ orcl>

Oracle-31-备份和恢复

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