We have a 3 node Exchange cluster with GCO option enable. RDS Replication seem not to be using maximum bandwidth. I looked at the perfmon counter VVR Remote Hosts (Data Transmitted), and am currently getting 1300 Kbytes/sec (1.3MBps) on a DS3 (5.6 MBps). While this was running, I transferred a 400MB file from local to remote via ftp, and got transfer rates as high as 2.9 MBps. So it seems to me that VVR is currently not using the �Maximum Available� bandwidth as it is currently set. Does this seem normal?
No it doesn't. Have you opened a support case? Obviously this is a mission critical app that your company has invested a lot of money in and you should call support to have them help you in a systematic way.
I'm actually using this forum as a last resort as support has done all that they could do. Question though, what would be the best replication mode & protocol for a 45MBps link?
I had to turn Latency Protection off as it out lock up the local host. Also, I was seeing better performance with TCP/UP as apposed to UDP (1400 Packet size) Should I try bumping up the packet size? If so what value?
Latency prot is seldom used and can result in very poor performance if you hit the high mark and have to throllt the app until it drains to the low mark. The difference shouldn't be more than 50.
Generally, all the consultants I have talked to found better performance with UDP. Are you seeing loss of pings if you do a hundred pings for example?
Packet size really is more dependent on the application write size. If you know what is being written by the app and make the packet too small then VVR has to split it up. IF you make it too large, then if your routers/VLAN is set to not pass fragmented packets, then you could get total loss of data transfer.
Have you checked to make sure the secondary isn't running with too little memory for receiving packets and is dropping and requesting retransmits?
Well, i've followed your advice & swich to Async UDP and bumped up the packet size to 64000 (Max) now, I'm getting 21Mbps (was getting 4Mbps before). I've set the receive buffer to 16MB from 4MB and the send to 256MB. MUCH BETTER!!!! Is this setting ok?
Sounds better to me. Just remember on any tuning be prepared to back it out if it gets worse. Keep track of your changes and try not to make too many at once.
And don't forget you can award points for correct answers.Message was edited by: Gene Henriksen
