How To Calculate The Required Network Bandwidth Transfer Of Redo In Data Guard Environments (Doc ID 736755.1)
APPLIES TO:
Oracle Database - Enterprise Edition - Version 9.0.1.0 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
GOAL
Goal is to transfer and apply redo as fast as possible in a Data Guard environment. To achieve this we have to calculate the required network bandwidth based on the redo generation rate on the primary database.
目标是在Data Guard环境中尽快转移和应用redo。为此，我们必须根据主数据库上的redo生成率来计算所需的网络带宽。
SOLUTION
The formula used (assuming a conservative TCP/IP network overhead of 25%) for calculating the network bandwidth is :
用于计算网络带宽的公式（假设保守的TCP/IP网络开销为25％）为：
Measuring the Peak Redo Rate 测量峰值Redo速率
Based on your business you should have a good idea as to what your peak periods of normal business activity are. For example, you may be running an online store which historically sees the peak activity for 4 hours every Monday between 10:00 am - 2:00 pm. Or, you may be running a merchandising database which batch-loads a new catalog every Thursday for 2 hours between 1 am - 3 am. Note that we say "normal" business activity - this means that in certain days of the year you may witness much heavier business volume than usual, e.g. the 2-3 days before Mother's Day or Valentine's Day for an online florist business. Just for those days, perhaps you may allocate higher bandwidth than usual, and you may not consider those as "normal" business activity.However, if such periodic surges of traffic are regularly expected as part of your business operations, you must consider them in your redo rate calculation.
During the peak duration of your business, run a Statspack snapshot at periodic intervals. For example, you may run it three times during your peak hours, each time for a five-minute duration. The Statspack snapshot report will include a "Redo size" line under the "Load Profile" section near the beginning of the report. This line includes the "Per Second" and "Per Transaction" measurements for the redo size in bytes during the snapshot interval. Make a note of the "Per Second" value. Take the highest "Redo size" "Per Second" value of these three snapshots, and that is your peak redo generation rate.
Note that if your primary database is a RAC database, you must run the Statspack snapshot on every RAC instance. Then, for each Statspack snapshot, sum the "Redo Size Per Second" value of each instance, to obtain the net peak redo generation rate for the primary database. Remember that for a RAC primary database, each node generates its own redo and independently sends that redo to the standby database - hence the reason to sum up the redo rates for each RAC node, to obtain the net peak redo rate for the database.
请注意，如果主数据库是RAC数据库，则必须在每个RAC实例上运行Statspack快照。 然后，对于每个Statspack快照，对每个实例的"Redo Size Per Second值求和，以获得主数据库的峰值重做生成率。 请记住，对于RAC主数据库，每个节点都会生成自己的redo，并将该redo独立地发送到备用数据库-因此，总结每个RAC节点的重做率，以获得数据库的峰值重做率的原因。
As an Alternative you can also get the 'Redo rate bytes per sec.' from V$SYSMETRIC_HISTORY, eg. 另外，您还可以获取'Redo rate bytes per sec.'。 来自 V$SYSMETRIC_HISTORY，例如
SQL> select * from v$sysmetric_history where metric_name = 'Redo Generated Per Sec';
or in a RDA-Output:
Performance - AWR Report - Statistic: "redo size"
Example:
Let us assume the redo rate is a 500 KB/sec. 让我们假设重做速率为500 KB /秒。
Required bandwidth = ((Redo rate bytes per sec. / 0.75) * 8) / 1,000,000 = bandwidth in Mbps Required bandwidth = ((512000/0.75) * 8) /1,000,000 Required bandwidth = 5.46 Mbps
Also see 另见
Data Guard Redo Transport & Network Configuration Data Guard重做传输和网络配置
And
Measuring Network Capacity using oratcptest (Doc ID 2064368.1) 使用oratcptest测量网络容量
for further Hints and Best Practices to setup the Network for Data Guard Log Transport Services 有关进一步的提示和最佳实践，以设置用于Data Guard日志传输服务的网络