Oracle 视图 V$FS_OBSERVER_HISTOGRAM 官方解释，作用，如何使用详细说明
本站中文解释
Oracle视图V$FS_OBSERVER_HISTOGRAM用于收集当前ASM实例的文件系统观察者收集的历史数据，并显示当前统计信息，包括同步活动，基本I/O，复制I/O等。其中asmon SID显示当前正在收集数据的观察者会话，数据库也包括此会话在内。
使用此视图，可以查询控制文件 I/O 等类型的近期操作，并通过分析这些数据来识别性能瓶颈，从而采取合适的措施增强性能。
要使用此视图，需要先启用观察者会话，以收集存储的统计信息。例如，以Database Control或客户端命令行下启用观察者会话，如下所示：
SQL> ALTER SYSTEM SET asm_disk_observer_enable = TRUE SCOPE=BOTH;
SQL> ALTER SYSTEM SET asm_file_observer_enable = TRUE SCOPE=BOTH;
要查询V$FS_OBSERVER_HISTOGRAM视图，可以使用以下常用SELECT语句之一：
查看一个实例中ASM所有磁盘工作情况：
SELECT inst_id, dg_name, avg_dlytim, avg_dly_mb, avg_trl_tim, avg_trl_mb,activity_time, active_frag
FROM v$FS_OBSERVER_HISTOGRAM;
查看指定实例和数据组中工作情况：
SELECT inst_id, dg_name, avg_dlytim, avg_dly_mb, avg_trl_tim, avg_trl_mb,activity_time, active_frag
FROM v$FS_OBSERVER_HISTOGRAM
WHERE inst_id and dg_name = ;
官方英文解释
V$FS_OBSERVER_HISTOGRAM displays statistics that are based on the frequency of successful pings between the observer and primary database for different time intervals. The wait event in this histogram is the observer’s wait until pings to the primary succeed.
The histogram displays only when there were ping failures between the observer and the primary database.
No rows are shown in this view for unregistered observers.
These statistics can be used to select an appropriate value for the FastStartFailoverThreshold configuration property for your environment.
| Column | Datatype | Description |
|---|---|---|
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The Fast-Start Failover observer name |
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The name of the host where this observer is running |
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The time interval between a pair of successful observer pings (ping-pairs) to this instance. Note that the values in this column are the upper bound of the inter-ping interval samples represented by a given histogram bucket. If The value in this column is the time (in seconds) that a ping failure lasted. |
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The number of ping-pairs with an inter-ping interval that corresponds with this histogram bucket. If all pings have been successful so far, this column has a value of 0. |
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The last time this row was updated |
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The ID of the container to which the data pertains. Possible values include:
|
See Also:
Oracle Data Guard
Broker for more information about the FastStartFailoverThreshold configuration property
Example
Assume that the following shows the status of observer’s pings to the primary:
Ping time Ping result --------- ----------- 1:00:00 SUCCESS 1:00:03 FAIL 1:00:06 FAIL 1:00:09 SUCCESS => Wait time of 6 seconds 1:00:12 SUCCESS 1:00:15 FAIL 1:00:18 FAIL 1:00:21 SUCCESS => Wait time of 6 seconds 1:00:24 SUCCESS 1:00:27 FAIL 1:00:30 SUCCESS => Wait time of 3 seconds
These ping results will result in the histogram view below:
WAIT_TIME WAIT_COUNT LAST_UPDATE_TIME 3 1 1:00:30 6 2 1:00:21 9 0 12 0 ...
In this case, the FastStartFailoverThreshold value should be set to larger than 6 because communication between the observer and the primary sometimes fails for 6 seconds.
