Hyper-V 2012 network transfer

jfish

jfish

jfish

Associate
Joined
24 May 2011
Posts
216
I am doing some tests with Hyper-V 2012 and network bandwidth - using iperf - this way I dont have to worry about disk I/O causing bottleneck

Network bandwidth between Hyper-V servers is about 600 MBit/s - This is ok not ideal but I can accept the result

Network bandwidth between virtual server 2008R2 on the same Hyper-V server - so using the interal virtual switch - I am getting 200 MBits/sec - which is shocking as I would expect much better transfer rate over the virtual switch

Anyone give an indication as to why I am getting such low network transfer

Windows 2008 R2 network speed on the virtual NIC is 10Gbps - However this what the operating system would see as the virtual network speed over the virtual switch.
 
rotor said:
My guess is you aren't using "server-grade" NICs.
Click to expand...

These are new HP Proliant server specs as follows

ProLiant DL380p Gen8
Windows Server 2012, x64 Datacenter Edition (Hyper-V)
4 x Embedded HP Ethernet 1Gb 4-port 331FLR Adapter
128 GB RAM

I cant see the servers hardware to be an issue, must be some Hyper-V network configuration
 
There isn't really that much to configure though, especially if these are clean installs. I would check you have the latest drivers, and also maybe try the latest Broadcom drivers (especially if they are newer than either the built-in Microsoft ones or the HP ones). I get around 970 Mbps on iperf at home between a Proliant MicroServer running 2012 R2 and a Windows 8.1 PC (via a cheap 3Com dumb switch). You should get nothing less from the hardware you have, so that's where I would start.
 
rotor said:
There isn't really that much to configure though, especially if these are clean installs. I would check you have the latest drivers, and also maybe try the latest Broadcom drivers (especially if they are newer than either the built-in Microsoft ones or the HP ones). I get around 970 Mbps on iperf at home between a Proliant MicroServer running 2012 R2 and a Windows 8.1 PC (via a cheap 3Com dumb switch). You should get nothing less from the hardware you have, so that's where I would start.
Click to expand...

been reading about VMQ - was wondering if that could cause the issue, its enabled on the virtual servers
 
Happy to be corrected, but I think the only supported guests for SR-IOV are 2012/R2, and Win 8x64? i.e. not 2008R2.

edit - if it's a virtual switch anyway the hardware/drivers would not make any difference.
 
jfish said:
been reading about VMQ - was wondering if that could cause the issue, its enabled on the virtual servers
Click to expand...

Disabling the VMQ fixed a whole load of slow network issues in VM's we had on a 2012R2 Hyper-V install
 
Last edited:
cokecan said:
Disabling the VMQ fixed a whole load of slow network issues in VM's we had on a 2012R2 Hyper-V install
Click to expand...

do I also have to disable it on the virtual server settings or just on the physical network cards.

Watched a video on MS about VMQ and how it was meant to improve network performance but from what I have read it causes more issues.
 
In theory VMQ seems like a great feature to stop a given VM from hogging all the bandwidth of a physical adapter.

I found disabling it on the VM config didn't do anything. Instead I disabled it on the host's network adapters using powershell:

While I'm sure you can do this all with one simple command piped into the next, I took my time and did it step by step :)

Use this to list all the network adapters on the host, taking note of the Name of each adapter
Code: 
Get-NetAdapter
Disable VMQ on the adapter specified (don't forget to use quotes if your adapter name is more than one word in length)
Code: 
Disable-NetAdapterVmq <adapter name>
Check enabled/disabled status of VMQ
Code: 
Get-NetAdapterVmq
When I did a bit more reading on this I found it seems to affect particlar brand of network adapters in 2012/2012R2 - I can't remember if it was Intel or Broadcom adapters?
 
cokecan said:
Disabling the VMQ fixed a whole load of slow network issues in VM's we had on a 2012R2 Hyper-V install
Click to expand...
In 2009/2010 I was getting BSODs on my 2008 R2 Hyper-V servers after installing an Intel driver and enabling VMQ (on the NIC -- the Intel driver presents it in the Advanced settings of the NIC). So it blows me away that 3-4 years later VMQ is still "in the news"! Wow.

Disabling VMQ stopped the BSODs, and once Intel released an updated driver (and re-enabling VMQ) the problem went away.
 
rotor said:
In 2009/2010 I was getting BSODs on my 2008 R2 Hyper-V servers after installing an Intel driver and enabling VMQ (on the NIC -- the Intel driver presents it in the Advanced settings of the NIC). So it blows me away that 3-4 years later VMQ is still "in the news"! Wow.

Disabling VMQ stopped the BSODs, and once Intel released an updated driver (and re-enabling VMQ) the problem went away.
Click to expand...

it also did this on HP Proliants with Broadcom nics as well. Driver plus firmware update and that resolved it so I am surprised as yourself this is still an issue.
 
It is pretty surprising how many people have had issues with this particular feature over the years.

Though it's making me wonder whether a driver and firmware update will allow me to turn it back on? Mind you, if this was present during the days of 2008 R2 then I'd expect a brand new HP Proliant Gen 8 with 2012 R2 to already have these updates present and possibly even applied?! Maybe I'm just being naive lol
 
cokecan said:
It is pretty surprising how many people have had issues with this particular feature over the years.

Though it's making me wonder whether a driver and firmware update will allow me to turn it back on? Mind you, if this was present during the days of 2008 R2 then I'd expect a brand new HP Proliant Gen 8 with 2012 R2 to already have these updates present and possibly even applied?! Maybe I'm just being naive lol
Click to expand...

our Gen 8's dont have the problem AFAIK or have never done anything o alert us to the fact. hmmm im worried now.....
 
You must log in or register to reply here.
Back
Top Bottom