Wednesday, January 30, 2008

Estimating the Network Band Width Required for Standby Database

For Better DR (Disaster Recovery) Site setup it is important to know the required Bandwidth Link Between the Primary and DR Site.

By using the Below formula, we can estimate the required Bandwidth Based on the Peak redo rate.

Required bandwidth = ((Redo rate in bytes per second / 0.7) * 8) / 1,000,000

= bandwidth in Mbps.

How to find a Redo Rate for a Database:-

Redo Rate can be found out from the Statspack report. 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. For example, this highest "Per Second" value may be 394,253 bytes or 385 KB.

Req'd Bandwidth = ((394253 / 0.7) * 8) / 1,000,000
= 4.5 Mbps