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Jumbo frames end-to-end? Or not?

 
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Occasional Contributor

Jumbo frames end-to-end? Or not?

Seeking advice on this one.  I have jumbo enabled on my CS240, the switches, and my storage stack on the ESXi 5.1 hosts/vDS are all using jumbo.  I created a new port group for iSCSI VM traffic and it will use jumbo.

Here is my question:  I have added two nics to a VM and configured them for iSCSI MPIO but I don't know if the Win2008R2 VM will need to use jumbo or not?  I searched here and didn't see an answer.

Opinions?

Thanks in advance.

Scott

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Valued Contributor
Solution

Re: Jumbo frames end-to-end? Or not?

Hi Scott,

You should enable jumbo frames across the entire network stack (host included) to realize the benefit that jumbo frames can offer. You can enable/use jumbo frames in Windows 2008 and later, and you will need to enable it on the network adapter(s) themselves. Here is a link to a basic article that outlines the steps involved:

Q. How do I enable jumbo frames? | Windows content from Windows IT Pro

For what it's worth, I would also submit that jumbo frames does not *always* equate to better performance. In most of the customer environments I'm exposed to, jumbo frames seems to be more common (and beneficial) where 10Gb Ethernet is in use and much less used in 1Gb environments.

Hope this helps!

Brandon Grieve

Nimble Storage

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Occasional Contributor

Re: Jumbo frames end-to-end? Or not?

Thank you.  That makes sense.

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Frequent Advisor

Re: Jumbo frames end-to-end? Or not?

Hi Brandon, can you explain why 10GB network gets more benefit out of jumbo frames? Thanks.

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Valued Contributor

Re: Jumbo frames end-to-end?  Or not?

Hello Jason. It generally has to do with the fact that 10G networks often carry larger data loads. So, larger frames means less transmissions need to take place on the network, thereby reducing overhead.

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Frequent Advisor

Re: Jumbo frames end-to-end? Or not?

I'd like to see a couple benchmark comparisons of Jumbo frames vs standard 1500 MTU on Nimble.

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Valued Contributor

Re: Jumbo frames end-to-end?  Or not?

We have two 460G arrays but the ESX hosts have two physical 1GB NICs per VM network. Without any formal before and after benchmarks I'd suggest Jumbo frames on the iSCSI network at very leas will improve performance since all roads lead to Rome as far as iSCSI traffic is concerned. Fewer transmissions/packets albeit larger ones. Not convinced whether general 1GB LAN traffic will benefit at all but the 1GB Switches have a 20GB Backplane so maybe still worth considering!

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Valued Contributor

Re: Jumbo frames end-to-end?  Or not?

The cost of 10GB cards for the hosts plus a concentrator or two rack up the costs!

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Valued Contributor

Re: Jumbo frames end-to-end?  Or not?

The point I'm trying to make is that if the storage has 10GB interfaces on iSCSI and you have a number of hosts connecting on the iSCSI network then it's many to one (dual port on Nimble) so definitely I'll recommend Jumbo frames for iSCSI traffic.

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Advisor

Re: Jumbo frames end-to-end? Or not?

Julez,


I've done some testing in the past with jumbo vs standard, and found there's little (couple of percent) performance gain from using jumbo frames. Personally I recommend against jumbo frames for reasons of simplicity. I have done installs at 2 big environments where we found out that not all of the layers (a NIC in one environment, a switch port in another) were configured for jumbo frames. This resulted in lower then expected performance as you can imagine.

Keep It Simple!


Arne