Active 11 years, 1 month ago. Viewed 8k times. Switches are Netgear JGS model web managed. Recommended for very large files. What have I missed? Improve this question. Teddy 5, 1 1 gold badge 21 21 silver badges 27 27 bronze badges. Rick Rick 3 3 silver badges 8 8 bronze badges. Are you using Jumbo Packets? Not that it should matter that much, but it will drastically reduce the amount of processing required by the 2k8R2 machine to forward the data to the iSCSI — Mark Henderson.
No, Jumbo Frames are not in use. We initially saw this with Jumbo Frames turned on and thought that was the issue. So, we disabled them restarted all, including the switch , brought it back to "plain vanilla" TCP and are still seeing this bizarre behaviour.
Have you got hardware flow control enabled on the switch and server NICs? I have just checked both - yes, hardware flow control enabled across all devices and also full duplex.
How are the NICs in the R2 machine arranged? If they're both on a PCI bus, you'll have a performance hit simply because the bus isn't fast enough to handle the traffic. Either you're using very slow drives, or there's a performance problem you've not identified yet somewhere in the system. Add a comment.
Active Oldest Votes. Improve this answer. Dan Andreatta Dan Andreatta 5, 2 2 gold badges 22 22 silver badges 14 14 bronze badges. We can't guarantee quick solutions - Experts Exchange isn't a help desk. We're a community of IT professionals committed to sharing knowledge. Our experts volunteer their time to help other people in the technology industry learn and succeed.
Plans and Pricing. Contact Us. Certified Expert Program. Credly Partnership. Udemy Partnership. Privacy Policy. Additionally due to lack of good flow control in Meg ethernet you do not specify if it is GigE or Meg it can be oddly faster to run your Meg at HALF duplex.
Sounds crazy, but really interesting when you test it in the real world! I agree verify the servers are not at half duplex and check the switch, crazier things happen.
You may need to set it to full duplex. This is a ggit NIC connected to a Mbit-switch. Both use setting auto, and in my experience duplex mismatch generates far worse performance, aswell as plenty of packetloss which I don't seem to have. After a few months, I stumbled over a huge error-counter in my switch for this expicit port, and oddly enough my comment about having both set to auto wasn't accurate so it seems.
Obviously, an auto-setting against a full duplex setting will revert the auto to half duplex "just to be sure". In any case, this may not be the issue here, but it is worth a shot. Adam Brand Adam Brand 6, 2 2 gold badges 27 27 silver badges 40 40 bronze badges. Can you explain WHY that matters? What does it do, and what might it be doing wrong, that is worth turning it off. I actually tried this, but no difference. However, I did not reboot the machine after this change, is that necessary?
I don't think a reboot is necessary, but it wouldn't hurt to try. Some of the things I tried Hope that helps someone! Community Bot 1. Molomby Molomby 1 1 silver badge 7 7 bronze badges. Luke Quinane Luke Quinane 1 1 gold badge 9 9 silver badges 20 20 bronze badges. John Rennie John Rennie 7, 1 1 gold badge 21 21 silver badges 34 34 bronze badges. Sign up or log in Sign up using Google.
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