Home » Server Options » Data Guard » How to Calculate Bandwidth Delay Product? (10gR2 ,RHEL)
How to Calculate Bandwidth Delay Product? [message #306166] Thu, 13 March 2008 01:51 Go to next message
waqas77
Messages: 1
Registered: March 2008
Location: Pakistan
Junior Member
In Data Guard Redo Transport and Network Best Practices for oracle database 10g R2 document, it has been recommended to set the size of TCP Socket buffers (RECV_BUF_SIZE & SEND_BUF_SIZE) to three times the bandwidth delay product (BDP).
You calculate BDP by multiplying Bandwidth with Round trip Time (RTT).
I have little confusion regarding RTT. When you use PING (and do not specify packet size) to find out RTT, you get RTT for 32 bytes packet. In case your Primary DB is generating redo at the rate of 4K/ms how would you calculate RTT? If i Simply ping my standby server from primary server with 32 bytes of data i get RTT equals to 1ms but if I ping standby server by sending a packet of 4K then i get RTT equals to 3ms. Which RTT value should i use in that case to find the BDP.
Re: How to Calculate Bandwidth Delay Product? [message #309154 is a reply to message #306166] Wed, 26 March 2008 11:46 Go to previous message
RichB
Messages: 3
Registered: March 2008
Location: California
Junior Member
The document does not clearly state a packet size used for the ping test. I'd probably start with using the higher one.

The defaults are rather low and are OS dependent ( according to the oracle Doc)

Looks like you're doing a local standby with that type of ping response. It would be interesting to hear if it really helps in a local standby. In our initial tests, our local network was good (like yours so it really wasn't that noticeable). Of course any less network 'chatter' is a good thing. We've used it for our remote standby which has a larger ping and the packet response is lower. It really made a big difference.

The calculation gives you a starting point to set your TNSNAMES.ORA/LISTENER.ORA. Once done, you can then monitor your network traffic and see if you should go up or down from there.

(network bits/second) * (1 bytes/8 bits) * (round trip time / 1000) * 3

(500000000*.125*.050)*3

Ours is half way across the country and our ping RTT is around .050 and our network pipe is 500Mbit/Sec so our BDP comes out to 9,375,000
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