Slow Lan speed

[Centosuser]

Hi Guys,

using windows 2012R2 64 bit on a VMWARE ESXI,

Copy between two servers of 2012R2 over 10GB NIC is extremely slow " 15MB/s "

any suggestions why ? on a different server the copy is like 120MB/s

I am on ESXI 6.0

latest patches are installed

latest VMware tools

thank you

[Centosuser]

no one ?

[unsichtbare]

What's the physical server?

Did you install ESXi with a vendor-customized ISO?

I worked on a Dell R620 once with 10Gb, and saw this because the local admin installed ESXi directly from VMware. Once we downloaded and installed the Dell-customized ESXi ISO from support.dell.com, network performed as expected.

[Centosuser]

the iso is a customizer one for Dell.

the same iso used on a different old Dell server which provide a full bandwish speed over the lan 120MB/s

[JinuV]

Which is your switch and check the MTU setting of your switch

[mcrape]

A few things to check:

• I assume VMware Tools is installed / up to date on both machines?
• Make sure you are using VMXNet3 NIC
• Are vSwitches the same between the two servers (e.g. same # of NICs on the port group)?
  • Make sure the switch isn't configured for promiscuous mode - this would add a lot of overhead
• Is it only the one VM that is affected on the host, or are you seeing slow speeds with other VMs on the host?

[Centosuser]

mcarpe,

thank you for your answer,

I have two switches one is for management attached to a physique NIC 1GB,

switch two is for production have 2 GB NICs and using NIC teaming.

the security mode : Promiscous mode and MAC address changes and forget transmits are not select

VMWARE 6.0.0, 3073146 build and latest VMware tools are installed

NICS are using vmx3 10GB,

MTU is 1500 ,

any more suggestions please ?

[mcrape]

Thanks for the details - so both VMs are connected to the same vSwitch, right? Is there another vSwitch that you can move one of the VMs to on the same host?

Do you have any other VMs on that host to try and copy files to? It would be interesting to see if the issue exists with one of those VMs or only when they try and talk to each other.

Are the VMs on the same subnet? I ask this to make sure that no external router is involved (i.e. all traffic is staying on that one host).

One other thing to consider is that this may be a Windows issue and not VMware. Take a look at this article detailing disabling SMB signing: How To Fix Windows Server Network Performance Problems -- Redmondmag.com

[unsichtbare]

I would also be interested in:

• How is the copy speed between two VMs on the same ESXi host and vSwitch
• Can you use iperf to run tests betwen VMs?

[Centosuser]

Dear Mcrap,

yes both VMs are connect to the same vSwitch which is for production , behind the vSwitch there is 2, 1 GB NICS , configured as TEAM.

yes the Vms are on the same subnet,  so the packets will be sent just inside the host using 10GB NICS,

unishbar , thank you for your answer

I've used a lan test to the file server to test the writ and read speed its comes with the below info :

writing ( Upload ) , 657.2121200 Mbps  and reading ( Download ) 763.0748080 Mbps

over the vSwitch with latest VMware tools what I am supposed to see as copying on  Mbps/s ?

[Centosuser]

anyone guys ?

I am stuck here and out of options.

[mcrape]

Hi Centosuser - those iperf numbers are definitely higher than what you are seeing vs. copying a file in Windows. Did you try disabling SMB signing as per that link I posted? It looks like it might be more of a Windows issue than a VMware issue.

[Centosuser]

thank you for your answer

the SMB was already applied on the group policy.

I am using pfsense firewall , probably this the issue ?

[unsichtbare]

Nothing wrong with pfSense.

[Centosuser]

thank you

I am trying to eliminate the issue .

any suggestion where to check ?

[mcrape]

A couple more thoughts:

• Do you have any A/V or IPS software running on the VMs?
• Are the VM's and/or VMDKs on the same storage?
• If you run esxtop, do either of the VMs have a rdy time?

[Centosuser]

thank you for your answer,

the VM are on the same storage SSD and same network segment .

no A/V or IPS Softwares on the VM.

I am not sure what you mean here ?

If you run esxtop, do either of the VMs have a rdy time?

[mcrape]

esxtop is a tool that can be run from the console of your host or over SSH. It will spit out a bunch of numbers (see here for great info - ESXTOP - Yellow Bricks). %RDY is of interest in that it will tell you if the VM is incorrectly sized, which could be causing some issues.

[Centosuser]

Thank you

I've run the ESXTOP and everything seems fine no issue noted.

any more suggestions to try ?

what am i supposed to get while copying files inside the VM over 10GB NICS ?

thank you