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Network configuration on VMware host

Posted on 2017-10-12
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Last Modified: 2017-10-16
Dear Wizards, can you please suggest on this scenario?

If a physical host (with 4 physical NICs) connect to Core Switch Cisco  3925, can we use the Link Aggregation Control Protocol (LACP) to increase the bandwidth for that host? And if so, how to increase the maximum bandwidth for virtual NIC of VMs inside that host?

Many thanks in advance!
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Question by:13L@CK_H3@RT
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19 Comments
 
LVL 2

Expert Comment

by:Ravi Kumar Atrey
You need to first team the physical NICs on the host machine and then you can then create it as virtual NIC. Since you wants to configure LACP on cisco, then you also need to enable LACP on host machine as well in the teaming settings.

https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004048

https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004088
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LVL 124
if this is VMware vSphere ESXi hosts LACP is only supported in Distributed Switches, not standard switches.

So a standard trunk no LACP will be sufficient just for standard switches. But do remember that physical configuration of the network switch dictates inbound traffic, outbound traffic is based on the teaming policy selected, and the two need to match for correct configuration.

All you need to do, is add a virtual machine network interface, make sure you use the VMXNET3 interface, and that has a network interface of 10GBpe - is that enough ?
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LVL 3

Author Comment

by:13L@CK_H3@RT
Dear Andrew, many thanks for you reply but I am not sure if I can understand you well. Could you please clarify?
- What is VMXNET3 interface?
- "virtual machine network interface" = "virtual NIC of a VM with a speed of 10 Gb/s"?

Is it required a downtime when we add new distribution switch and configure LACP on an environment of standard switch?
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LVL 124
VMXNET3 is the virtual network interface in the Guest Virtual Machine.

Firstly VMware vSphere supports two different  networking setups...

1. Standard Switches
2. Distributed Switches

LACP is just a stack/trunk protocol. You can still build four port trunks without LACP.

How many ESXi hosts do you have ?
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LVL 3

Author Comment

by:13L@CK_H3@RT
Hi, I have 4 ESXi hosts, each of them have 1 physical network cable connected to Core switch Cisco 3560.

currently we use standard switch setting, but seems like the read/write operations in VM are slow. Just for your information about our diagram:

HP MSA 2040 (Raid6)--------- 8 x Fibre optical ------------ 4 Hosts HP Gen9 -----------4 x 1 Gb/s ------------- Core switch Cisco 3560 ------------ Router Cisco 3925 --------- ------ Internet
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LVL 124
It could be a number of reasons read/write access are SLOW!

All VMs should have VMware Tools installed and VMXNET3 interfaces installed  - that's a given.

What data and diagnosis have you performed to indicate the bottleneck is in the 4 x 1GB/s network interfaces ?
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LVL 3

Author Comment

by:13L@CK_H3@RT
Yes, we installed VMware tools for all 20 VMs, not sure how to check if VMXNET3 interfaces installed, could you please suggest?

Please find the attachments for the NICs, SAN and Disk info: sometimes I saw the disk speed peaked to 241 MB/s but decrease immediately. The average speed is about 60 MB/s, do you think it is too slow for a VM (RAM 80GB, 40 CPUs)?
NIC.PNG
Disk.PNG
SAN.PNG
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LVL 124
Yes, we installed VMware tools for all 20 VMs, not sure how to check if VMXNET3 interfaces installed, could you please suggest?

VM Settings - check the nic ?

You've assigned a VM with 80 vCPUs ?
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LVL 3

Author Comment

by:13L@CK_H3@RT
No, 40 vProcessors. is it a problem?
12.PNG
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LVL 124

Accepted Solution

by:
Andrew Hancock (VMware vExpert / EE MVE^2) earned 1000 total points
Could be....and if you've added 40 vCPU, and if the VM needs them, it may be better that this server is physical and can use all the resources.

What was the thinking or logic of adding 40?

what is the server, and what function does it perform, to have 40 vCPU allocated to it....

vSMP (virtual SMP) can affect virtual machine performance, when adding too many vCPUs to virtual machines that cannot use the vCPUs effectively, e.g. Servers than can use vSMP correctly :- SQL Server, Exchange Server.

This is true, many VMware Administrators, think adding lots of processors, will increase performance - wrong! (and because they can, they just go silly!). Sometimes there is confusion between cores and processors. But what we are adding is additional processors in the virtual machine.

So 4 vCPU, to the VM is a 4 Way SMP (Quad Processor Server), if you have Enterprise Plus license you can add 8, (and only if you have the correct OS License will the OS recognize them all).

If applications, can take advantage e.g. Exchange, SQL, adding additional processors, can/may increase performance.

So usual rule of thumb is try 1 vCPU, then try 2 vCPU, knock back to 1 vCPU if performance is affected. and only use vSMP if the VM can take advantage.

Example, VM with 4 vCPUs allocated!

My simple laymans explaination of the "scheduler!"

As you have assigned 4 vCPUs, to this VM, the VMware scheulder, has to wait until 4 cores are free and available, to do this, it has to pause the first cores, until the 4th is available, during this timeframe, the paused cores are not available for processes, this is my simplistic view, but bottom line is adding more vCPUs to a VM, may not give you the performance benefits you think, unless the VM, it's applications are optimised for additional vCPUs.

See here
http://www.vmware.com/resources/techresources/10131

see here
http://www.gabesvirtualworld.com/how-too-many-vcpus-can-negatively-affect-your-performance/

http://www.zdnet.com/virtual-cpus-the-overprovisioning-penalty-of-vcpu-to-pcpu-ratios-4010025185/

also there is a document here about the CPU scheduler

www.vmware.com/files/pdf/perf-vsphere-cpu_scheduler.pdf

https://blogs.vmware.com/vsphere/2013/10/does-corespersocket-affect-performance.html
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LVL 3

Author Comment

by:13L@CK_H3@RT
Yes that one is an Exchange server 2016, serving about 900 users, the CPU utilization reduces significantly when we increase the vProcessor, and yes we have Ent plus license.

Do you think the SAN storage is the reason for slow read/write?

The high RAM in picture is due to our import data process, normally it is about 60%, CPU is about 10%
34.PNG
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LVL 124
So you really think 40 virtual processors are necessary after reading my last post?
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LVL 3

Author Comment

by:13L@CK_H3@RT
Hi andrew, I am doing a test to measure the I/O rate when varying the vCPU of VM.

Apart from the number of vCPU, is there any other factor which can affect the I/O performance?
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LVL 124

Assisted Solution

by:Andrew Hancock (VMware vExpert / EE MVE^2)
Andrew Hancock (VMware vExpert / EE MVE^2) earned 1000 total points
I would have a look through this EE Article I wrote

SAN storage can affect I/O
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LVL 3

Author Comment

by:13L@CK_H3@RT
Hi, this is the first part of a test. I will keep the RAM unchanged 20GB and varying the vCPU.

micro-benchmark is measuring the taken time to run command 1000 times. Repeat 100 times and calculate the average value. Do you think this test is suitable?

This is the command on PowerShell:
for ($n=1;$n -le 100;$n++) {Measure-Command {for($i=1; $i -le 1000; $i++){echo Hello world}} | find "TotalMilliseconds :"}

Open in new window

test.PNG
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LVL 124

Assisted Solution

by:Andrew Hancock (VMware vExpert / EE MVE^2)
Andrew Hancock (VMware vExpert / EE MVE^2) earned 1000 total points
by using a VM with 40 vCPUs will affect performance on all the other VMs.

What is the host ?

and if you did need a VM which needed so much resource why would your virtualise it.

I would look at performance overall on the host.
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LVL 3

Author Comment

by:13L@CK_H3@RT
please see the attachment for the host's information.

Because we have to deploy Exchange system for 6 subsidiaries and some other servers so we choose VMware to save money. The VM which have 40 vCPU is standing alone in one host. The VM which I am testing on is in other host (in the picture)
esxi.PNG
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LVL 124

Assisted Solution

by:Andrew Hancock (VMware vExpert / EE MVE^2)
Andrew Hancock (VMware vExpert / EE MVE^2) earned 1000 total points
not sure how you are saving money, if a VM has all the resources associated with it, you might as well remove the hypervisor, and have the OS on Bare Metal accessing all the resources as the hypervisor will slow the VM down!

I think you seriously need to look at the VM requirements for this Exchange Server, it's not benefiting from Virtualisation by assigning all the vCPUs to it.

It's possibly CPU oversubscribed and running slower than it should.

see here

http://msexchangeguru.com/2016/06/07/exch-proc-calc/
0
 
LVL 3

Author Closing Comment

by:13L@CK_H3@RT
Many thanks for your answers.
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