XenServer 6.1: Strange network performance in both Win2K8R2 and Win2012 VMs...

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VanFanel89

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Gents,

I am experiencing a bit of an odd network performance issue in both my 2008 R2 DC and 2012 DC Windows Server installs.

Both have XenTools installed and all latest Windows Updates.

In both situations, when I copy a large file to the VM, I can max out at about 80-95 mb/s (80 on the 2008 VM, 95 on the 2012) consistently. But when I copy something FROM the VM to another machine, they both fluctuate - between 75 mb/s to 35 mb/s in what almost looks like a sine wave... it will go up and down, up and down...

I tried disabling all offload options under the network interface configuration, but that did not resolve the problem. In fact - I left all the NIC settings as default on the 2012 VM - the performance is the same.

I tried swapping Xen to using the ol' Linux Bridge vs. Open vSwitch... no difference. Disabled bonding/LACP - no different...

Has anyone else experienced this? Oddly enough - I am fairly certain that the 2008 R2 machine worked just fine a few weeks ago.

Thanks in advance!
 
Where are you copying from to. On box, off box, do they have dedicated nics?

What program are you copying with? Robocopy or similar or UI. The UI copy can be slow on its own and can be cpu related.
 
The copying is done from/to my laptop via a ProCurve switch to dedicated NICs for the VM using regular GUI.

Up until recently copying to and from my laptop would achieve maximum speed, but now, when copying from my laptop to the VM - I get max speed, but to my laptop from the VM - fluctuating speeds.

This is all done via standard Windows GUI; CPU utilization is low (the box has two Opteron 6276's and the laptop is a Core i7).
 
EDIT: See my next post***

Has any config changed on the switch(es)?

I'm running 6.1 with all the latest hotfixes running on HP ProCurve's

VM running on XenServer > ProCurve Switch > ProCurve Core Switch > ProCurve Switch my desktop is on > then finally my desktop and I'm still able to hold a consistent 70-75MB/s

My desktop even has a Braodcom NIC. Not as bad as Realtek, but not my preferred straight Intel NIC.
08r2-vm.png


Have you updated or changed drivers for your NIC on the laptop by chance?
 
I spoke too soon, I see exactly what you're talking about now. Sending data back to the server VM.

More work for me, thanks! :) lol

hmmmmm.png


I'm going to venture a guess and say it's XenServer related after all...
 
Ha! I get to feel stupid again today. It helps if I try another VM that isn't under load with 30-40 users.

unloaded-vm.png


I'm going to play around to be sure, but there might be something else at play. Also I was asking about iSCSI wondering how your write speeds are compared to your read speeds.

EDIT: I also found this, may be of some help. I've found a few other similar that it applies to 03 and 08, not just 03 as it shows here. Granted this dates back to the 5.x branch, but that doesn't necessarily mean something did not slip through.

http://www.xenappblog.com/2010/citrix-xenserver-slow-network-performance/

Either way, good luck. :)
 
MikeTrike - thanks for checking. My setup is Box -> ProCurve 2824 -> Laptop. Admittedly my laptop does have a RealTek NIC (MSI Laptop) BUT it is able to push nearly 113 MB/s when copying from it to the VM. And, as I mentioned earlier, it used to work just fine with no fluctuations. Now - I am still able to copy to the VM no problem... it's from the VM that fluctuates.

The VM I am using is not overly taxed; however another VM on the box eats a lot of Disk IO (5 drives in RAID5 on an LSI hardware controller + one hotspare). I thought perhaps that was the problem and had the VM shut down... but nope, same problem.

I'll try the registry hacks - I've done that before but reinstalled the VM; don't think I've done it again.
 
Well I be damned... Did the disable task offload via registry, rebooted - and now I am getting a nice 95 mb/s copy from VM to laptop!

I wonder wtf happened before....... but it's working! Yay! Let's hope it continued working...
 
VanFanel89 said:
Well I be damned... Did the disable task offload via registry, rebooted - and now I am getting a nice 95 mb/s copy from VM to laptop!

I wonder wtf happened before....... but it's working! Yay! Let's hope it continued working...
Click to expand...

Awesome! I feel better about me being stupid twice now. lol

One out of three isn't too bad... :D
 
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