Slow network performance...

[sikboater]

I just set up a ESXi 4.0 host that will house a few different guest on it. It is installed on a Dell 1950 server with two 2 core processors and 4 GB ram.

The problem I am having is the network performance is very slow when copying files form a computer in the network (outside the VM machine) to a guest windows 2003 or 2008.

I have verified all the network cards are set to 100/Full and the switch (cisco 2900) is also set that way.

I have also tried to change the network card in the guest OS systems. (vmnet 3, vmnet 2, or flexible).

None of these changes seem to help.

I can copy files to other computers on this switch (not on the ESXi server) and the speed is good, just the virtual machines are very slow....

Any ideas I can try? Do I need to try a different version of ESX server?

Please let me know if there is any further info needed...

Thanks for any help provided!

Tim

[Dave_Mishchenko]

Hi Tim, welcome to the VMware Community forums. What sort of speeds are you seeing? It may be helpful to test network connectivity and disk I/O seperately as your network copy depends on both to operate quickly. Do you see similar slowness when copying from a VM on that some host? When VMs on the same vSwitch (and VLAN if configured) communicate the traffic doesn't go out to the physical NIC so that would eliminate your physical networking as an issue if it is still slow. What sort of controller does the host have and have you tried a disk test? Something like IOmeter will give you an idea of what sort of disk performance you're getting. Depending on the controller in the VM you might see a boost if you add battery backed write cache.




Dave

VMware Communities User Moderator

New book in town - vSphere Quick Start Guide -http://www.yellow-bricks.com/2009/08/12/new-book-in-town-vsphere-quick-start-guide/.

Do you have a system or PCI card working with VMDirectPath? Submit your specs to the Unofficial VMDirectPath HCL - http://www.vm-help.com/forum/viewforum.php?f=21.

[sikboater]

Hi Dave,

The speeds are pretty slow the start out at around 700 KBps and then drop off to 100 KBps. If you copy from guest to guest on the same host the speeds are fast, about 6000 KBps. If I try to go from the guest server (win2k3) to another computer in the network, I still get the same slowness...

It seems to me to by a problem on the physical side of the ESXi server???

I have attached a couple of screen shots from vSphere, I don't think they really help but gives you an idea....

I have not looked into the physical disk test on the host server yet, but will if you think I should...

Thanks

Tim

[J1mbo]

Please post info about the vSwitch config - how many NICs are connected? What load balancing is in use?

But it sounds like packet loss, try a different network cable and then NIC, different switch port etc. Try a cross-over cable to a laptop to eliminate the switch.

I would personally configure all NICs and pSwitch ports to auto/auto. Also your clients need to be correct at both ends also.

HTH

Please award points to any useful answer.

[sikboater]

I have tried both manually setting all nic's to auto and manually 100/full. No difference in preformance.

I did figure out that if you you download from the VM to a computer on the network or on a crossover cable directly attached it preforms as expected. But uploading is still very slow.

No different if using a crossover and laptop compared to the using the switch.

Here are some screen shots from the network config....

Any more ideas? I have not changed any of the default settings.....

Thanks

Tim

[Dave_Mishchenko]

I did figure out that if you you download from the VM to a computer on the network or on a crossover cable directly attached it preforms as expected. But uploading is still very slow.

When you did your VM to VM test where you downloading from the same VM that you used in the above test? What sort of file copy are you doing?

Dave

VMware Communities User Moderator

New book in town - vSphere Quick Start Guide -http://www.yellow-bricks.com/2009/08/12/new-book-in-town-vsphere-quick-start-guide/.

Do you have a system or PCI card working with VMDirectPath? Submit your specs to the Unofficial VMDirectPath HCL - http://www.vm-help.com/forum/viewforum.php?f=21.

[J1mbo]

There might be a couple of issues at play here.

First, if connecting with a crossover cable, both ends absolutely must be set to the same, and preferably autonegotiate. It appears from the screenshots that the NIC is set at 100/F, in which case the other end would connected at 100/H and cause the fast one direction slow the other behaviour in the direction described.

Second, does this server have battery-backed write cache installed on it's PERC array controller (BBWC)? If not, this could be contributing greatly to slow uploads.

HTH

Please award points to any useful answer.

[sikboater]

Ok, This ended up being the issue....

I tried again to setup the laptop using crossover cables and also checked the speed. I set both to auto. I got fast up and down speeds... This lead me to a new cable to the switch (checking all settings to make sure they are the same); no change.

I rechecked all the settings and set everything to auto, making sure they negotiated the 100/full (as that is what the switch is). I also loaded the VMXNET 3 network driver on the VM machine. (this was needed to get it to auto negotiate to 100/full).

I graphed the resulting transfers on the cisco switch and the up and down were the same and utilizing the correct speeds...

Problem solved.... It was a interesting problem, this is the first time I have tried to put some VM servers to use in my network at work and my boss is not 100% sold and does not want me to spend a lot of time on it. Now I know to check everything and were to look for this problem...

Thanks for everyone's help!!

Tim