如何计算Data Guard环境中Redo所需的网络带宽传输 (Doc ID 736755.1)

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：

Required bandwidth = ((Redo rate bytes per sec. / 0.75) * 8) / 1,000,000 = bandwidth in Mbps

所需带宽 = ((每秒redo生成率字节/0.75)* 8)/1,000,000 = 以Mbps为单位的带宽

Measuring the Peak Redo Rate  测量峰值Redo速率

Use the Oracle Statspack utility for an accurate measurement of the redo rate.  使用 Oracle Statspack 来准确测量重做率。

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.

根据您的业务，您应该对正常业务活动的高峰期有所了解。 例如，您可能正在经营一家在线商店，该商店过去会在每周一的上午10:00至下午2:00之间看到4个小时的高峰活动。 或者，您可能正在运行一个商品数据库，该数据库每个星期四在凌晨1点至凌晨3点之间进行2小时的批量加载。 请注意，我们说的是“正常”的业务活动-这意味着在一年中的某些日子，您可能会目睹比平常大得多的业务量，例如 在线花店业务在母亲节或情人节前2-3天进行。 仅在那些日子里，也许您分配的带宽可能会比平时高，并且您可能不会将其视为“正常”业务活动。但是，如果经常将这种周期性的流量激增视为业务运营的一部分，则必须将其考虑在您的重做率计算内 。

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.

在您的业务高峰期间，请定期运行 Statspack 快照。 例如，您可以在高峰时段运行三遍，每次运行五分钟。 Statspack 快照报告将在报告开头附近的 "Load Profile" 部分下包含 "Redo size" 行。 该行包括快照间隔内redo大小的"Per Second" and "Per Transaction"度量。 记下"Per Second"值。 取这三个快照中最高的"Redo size" "Per Second"值，这就是您的峰值redo生成率。

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