1.Oracle維護着兩類重做日誌文件：在線（online）重做日誌文件和歸檔（archived）重做日誌文件。
2. ARCHIVE LOG LIST ----查看數據庫是否處於歸檔模式（用sys用戶登錄，顯示當前用戶：show user）
3.在線（online）重做日誌文件位置：select * from v$logfile；歸檔（archived）重做日誌文件位置：show parameter log_archive_dest.
4.路徑查詢：
1.參數文件和網絡連接文件 SQL> show parameter spfile;
2.控制文件SQL> select * from v$controlfile;3.數據文件SQL> select FILE_NAME from dba_data_files;
4.在linux測試機上用top命令可以查看內存大小；
深入logbuffer：
第一數據庫實例：SGA_MAX_SIZE specifies
the maximum size of the SGA for the lifetime of the instance. sga_max_size指定了實例一生中可以使用的sga的最大值。（也就是說實例只要不死，就只能用這麼多內存。想增加？那不好意思，死一次吧，重啓實例）。
SGA_TARGET specifies the total size of all SGA components. If SGA_TARGET is specified, then the following memory pools are automatically sized:
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Buffer cache (DB_CACHE_SIZE)
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Shared pool (SHARED_POOL_SIZE)
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Large pool (LARGE_POOL_SIZE)
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Java pool (JAVA_POOL_SIZE)
If these automatically tuned memory pools are set to non-zero values, then those values are used as minimum levels by Automatic Shared Memory Management. You would set minimum values if an application component needs a minimum amount of memory to function properly.
The following pools are manually sized components and are not affected by Automatic Shared Memory Management:
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Log buffer
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Other buffer caches, such as KEEP, RECYCLE, and other block sizes
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Streams pool
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Fixed SGA and other internal allocations
The memory allocated to these pools is deducted from the total available for SGA_TARGET when Automatic Shared Memory Management computes the values of the automatically tuned memory pools.
sga_target指定了所有sga組件的總大小。其實也是sga的最大值，只不過不是一生中最大值，而是當前可使用的sga的最大值。因爲sga_target是可以動態修改的，你隨時可以調大調小，但是不可能超過sga_max_size，除非你死了）。
也就是說當sga_target<sga_max_size的時候，是sga_target控制sga的大小。
這也就解決了很多人對於sga_target設定大小的糾結，在我看來,很簡單，sga_target 應該甚至必須等於sga_max_size，只有這樣你所設定的內存大小才能被充分利用。
人家官方文檔寫的很嚴謹，一切奧祕盡在lifetime一個單詞而已。
內容引用網址：http://blog.csdn.net/x_blacke/article/details/7549682這說明logbuffer值是SGA內存的一部分區域。
DB_RECOVERY_FILE_DEST:
DB_RECOVERY_FILE_DEST specifies the default location for the flash recovery area. The flash recovery area contains multiplexed copies of current control files and online redo logs, as well as archived redo logs, flashback
logs, and RMAN backups.
Specifying this parameter without also specifying the DB_RECOVERY_FILE_DEST_SIZE initialization parameter is not allowed.
See Also:
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Oracle Database Backup and Recovery Basics for information on setting up and configuring the flash recovery area
