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5 Replies Last post: Sep 18, 2007 1:54 PM by Jason Heltne  
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csindelar
7 posts since
Sep 10, 2007

Sep 16, 2007 11:28 AM

vmkernel configuration


When configuring hosts for vmotion, would more performance be gained by connecting multiple ESX hosts on a private LAN (via a standalone switch) compared to running the traffic over the core network?

Or does the vmkernel connection need to be on the same LAN as the vmnetwork or service console.

Please advise.

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stuart
1 posts since
Sep 16, 2007
1. Sep 16, 2007 11:53 AM in response to: csindelar
Re: vmkernel configurationd
It makes sense that the less contension there is, the quicker a VMotion can take place, and we know it needs (or is recommended) 1GB.

Having the VMotion traffic on a seperate subnet is a good idea and running it on a seperate switch will work perfectly.

You can even run VMotion via a cross-over cable between 2 servers if you wanted. (I've tested this).
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csindelar
7 posts since
Sep 10, 2007
2. Sep 16, 2007 12:00 PM in response to: stuart
Re: vmkernel configurationd

Thanks for the quick response. Since I have more than two hosts, I'll have to try the switch. It made sense in my mind but I just wanted another opinion.

Thanks again.

Corey

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Jason Heltne
2 posts since
Sep 18, 2007
3. Sep 18, 2007 12:31 PM in response to: csindelar
Re: vmkernel configuration
We have 18 VMWare 3 hosts (and growing) and we have a dedicated VLAN for console and seperate for VMotion. We decided to treat the console network like a cluster heartbeat network (although still routed), with nothing else on it since we were concerned that failovers could happen if lots of VMotion traffic was happening. Its now a non-issue.
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freshmaker13
1 posts since
Sep 10, 2007
4. Sep 18, 2007 1:22 PM in response to: csindelar
Re: vmkernel configurationd

I attended a tuning session at VMWorld and the party line was "use a second gig link for redundancy but you don't need the extra bandwidth for VMotion". As has been discussed here, you want to keep VMotion on its own VLAN. It was also suggested that pairing VMotion and the Service Console on the same subnet was acceptable and supported. You can make the VMotion and the Service Console interfaces redundant to each other using port groups.
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Jason Heltne
2 posts since
Sep 18, 2007
5. Sep 18, 2007 1:54 PM in response to: csindelar
Re: vmkernel configuration
The catch there is "supported" vs would you do it in a large environment. Mine is gonna be at least 25 ESX hosts on IBM 3950 8 way-dual core servers (soon to be 3i) with 30+ guest per host, so I wouldnt do that in my environment. We have monitored our vmotion VLAN and have seen us max out our bandwidth when a host failed and all the VMotioning was going on. It was to the point that we couldnt get to a host through virtual center, and this is on Cisco 6500 class gb port switches. I personally think the answer is, it depends on your environment and guest sizes and failover configuration and...... But the safe bet is to VLAN them off in a larger environment.

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