Can changing MTU to on FreeNAS VM cause ESXi not be able to connect?

[JohnnyBeGood]

Hi,

I have ThinkServer TS140 and in it M1015 flashed to IT mode.
I'm following this guide https://b3n.org/freenas-9-3-on-vmware-esxi-6-0-guide/
but it looks like after changing MTU to 9000 and reboot I cannot connect to ESXi via web interface or Windows client?
Its running and I can ping it but can't connect. I already reinstalled ESXi yesterday and today it happened again.
I was under impression that whatever I do to FreeNAS VM it shouldn't have any effect on ESXi.
Any replies are welcome!

Thanks

 

[jgreco]

Jumbo frames are a bad idea unless you're willing to make sure each and every device is properly configured and perfectly supported. This most certainly includes the ESXI vSwitch, your client, your choice of network chipset, etc ...

 

[JohnnyBeGood]

Ok, I will re-install again but this time try to leave MTU alone and leave default E1000 instead of changing to VMXNET3
Just trying to narrow down what is causing this issue.

 

[depasseg]

Why not ask the B3n.org group for help? Or vmware? You changed a network setting in a VM and you can no longer access the hypervisor and you come here for help? And furthermore, this mtu 9000 issue looks like it's addressed in the guide you followed. Just search that page for "9000".

 

[depasseg]

I was under impression that whatever I do to FreeNAS VM it shouldn't have any effect on ESXi.

This is true. Which is why I'm left scratching my head wondering what else might have been changed.

 

[joeschmuck]

I left the MTU settings alone in my ESXi setup, the extra possible throughput isn't worth the hassle. BTW, I used that guide also when setting up my ESXi system and just used the parts I wanted to use (I read the notes of caution about the MTU 9000 setting issues and didn't want that) and things are working great. I run FreeNAS, 2 instances of Sophos, Ubuntu, and a Windows VM, nothing real fancy but I have room to expand quite a bit.

I would ask you what your usage is for your ESXi system and if you plan to run several VMs which need to talk to each other over IP, then VMXNET3 should be used, but you don't need an MTU of 9000 for big gains, the VMXNET3 driver should allow for super high speed transfers between the VMs, but this does not translate into faster external throughput. So long as you understand this, you will be fine.

EDIT: Also ensure you are running the latest version of ESXi.

 

[JohnnyBeGood]

Why not ask the B3n.org group for help? Or vmware? You changed a network setting in a VM and you can no longer access the hypervisor and you come here for help? And furthermore, this mtu 9000 issue looks like it's addressed in the guide you followed. Just search that page for "9000".

I guess I wasn't clear in my question I just needed confirmation that changing something on FreeNAS VM won't have any effect on ESXi. I already posed question couple of days ago on VMware but no reply. Reason for not posting on B3n.org was that I thought its more of a blog than discussion board but that will be next step.

 

[JohnnyBeGood]

I left the MTU settings alone in my ESXi setup, the extra possible throughput isn't worth the hassle. BTW, I used that guide also when setting up my ESXi system and just used the parts I wanted to use (I read the notes of caution about the MTU 9000 setting issues and didn't want that) and things are working great. I run FreeNAS, 2 instances of Sophos, Ubuntu, and a Windows VM, nothing real fancy but I have room to expand quite a bit.

I would ask you what your usage is for your ESXi system and if you plan to run several VMs which need to talk to each other over IP, then VMXNET3 should be used, but you don't need an MTU of 9000 for big gains, the VMXNET3 driver should allow for super high speed transfers between the VMs, but this does not translate into faster external throughput. So long as you understand this, you will be fine.

EDIT: Also ensure you are running the latest version of ESXi.

Yes, my plan to have at least 2 VMs to talking to each other. I'm on the latest ESXi 6.0 Update 2

 

[JohnnyBeGood]

I've narrowed down my issue. After every change I would do a reboot of ESXi and found that after I set private IP (192.168.1.112) here

that is out of DHCP server range after reboot I no longer can connect.
Only if I re-install and check "Obtain IP settings automatically" I can continue without any issue.
What is purpose of this screen does any one knows?

 

[depasseg]

And this is the reason that virtualizing FreeNAS isn't recommended.

Don't try virtualizing FreeNAS before you have a good grasp of the fundamentals of ESX.

 

[jgreco]

good grasp of the fundamentals of ESX.

Might more accurately be "good grasp of the fundamentals of networking."

You cannot just put random numbers in random boxes and hope for things to work.

 

[pirateghost]

You cannot just put random numbers in random boxes and hope for things to work.

Speak for yourself. I've made a living doing exactly that!

 

[depasseg]

Speak for yourself. I've made a living doing exactly that!

Possible proof that it's better to be lucky than good?!

 

[Mlovelace]

@jgreco this is threefer for your what not to do thread. You've got clueless network setup, jumbo frames, and virtualized freeNAS with no knowledge of ESXi.