Limit amount of data sent between two servers

Dragon0x40
Dragon0x40 used Ask the Experts™
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If a database is replicating from one server across a WAN link to another server and that replication is utilizing the link at 100% then can the servers be set to replicate the database at a slower speed?

Maybe manually decreasing the TCP/IP window size? I know the NIC could be set to 10mb but that is too slow and 100mb is too high. How about 100mb half duplex?

I would like to limit the max bandwidth to no more than 35 to 40MB.

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Hello,

You shouldn't have to adjust your NIC setup, leave that set to either auto or the max supported speed.  Have a look at these links as they pertain to replication throttling which may work for you.

http://stackoverflow.com/questions/4822434/throttling-sql-server-replication

http://technet.microsoft.com/en-us/library/cc966539.aspx

Author

Commented:
Thanks for the links but I did not see where the replication throttling was in those links. Mostly discussed optimizing or increasing replication speed.

My understanding is that one server is Oracle and the other is an MS SQL server. The SQL server is copying all the records from the Oracle database but it is taking up too much of the WAN link bandwidth.

The question is how to slow this data replication down?
I see.  Sorry those didn't work out.  But try googling 'sql 2008 replication throttling'.  I'm sure there has to be something in the search results that helps.

Sorry I couldn't be of more help.
Sr.Net.Eng
Top Expert 2011
Commented:
MAG03 and I addressed this in another question, but the only solution you can do to contain that traffic is shape or police it. The fact is that database transfers are traffic heavy. Usually needing OC3 level connections, or QOS to prevent the link from being saturated. You could try using priority 35000 under your service policy that we provided in the other question. See if that help.
Aaron TomoskyDirector of Solutions Consulting

Commented:
What are your routers? There maybe bandwidth management in them. I was just playing with a sonicwall tz210 today that ha some neat stuff.

Author

Commented:
Don't the two servers negotiate the speed of the transfer in order to fill the WAN link?

Is there no way to influence the amount of data that the downloading server requests?

I was thinking that if the TCP/IP window size could be manually set somehow that could limit the speed of the transfer.

What if we only had several T1 lines multilinked together would the transfer fail or throttle down?

Does anyone have experience with using QOS to limit database transfers? Does the database get corrupt due to dropped packets? Currently we are not experiencing any dropped packets on the link but the link is fully saturated some of the time during the transfer.

Not questioning the proposed solution of QOS with shaping or policing but I would need to be sure the database does not get corrupt.

Maybe an OC3 is the best answer.

Am I correct in assuming that if I apply shaping or policing there is a high probability that some packets are going to be dropped? I don't think the router has enough memory to hold all the packets in a buffer without dropping any packets?
SouljaSr.Net.Eng
Top Expert 2011
Commented:
OC3 or Metro Ethernet. Metro Ethernet would be cheaper. On another note, I bet the tcp window is probably being already downsized by the two servers when they negotiate being that the wan link is the bottleneck. Think about if this was a tranfer between two database servers on the same lan, you would most likely be using a gigabit connection for the transfer.
Aaron TomoskyDirector of Solutions Consulting

Commented:

Author

Commented:
I have contacted a vendor and willl post updates

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