HyperV failover cluster - virtual network switch names

HI,
we have a production HyperV cluster of 3 datacenter 2008R2 hosts, connected to a SAN via sas. we have 3-4 servers on each.
I have created a Test server on a hyperv host and wanted to test a 'live' migration - but it fails complaining a resource is offline or failed (there are none). I have noted in the event log it has Virtual network switch errors saying it cant find 'virtual network A' ...

At the beginning to try and help me track what virtual server was connected to what NIC i thought id be clever and tag them a unique name. Then it seems it failed failover validation and i worked out to migrate the server to another host it needs to see the same 'name' network on the other hosts.... so i renamed all the virtual networks back to the default - that went through ok.

So it seems i have an issue where it wont let me migrate a machine from host to host and it looks like it might still be refering to the old virtual names.

servers run 24/7 and i have not rebooted them for some time.

Is it possible to re-run the validation - which i assume will knock the resources offline - without causing a problem and would this enable the cards to be correctly named in the cluster?

I just dont want the situation whereby i run the validation again and it fails and i have a broken cluster or somthing disastrous like that...

I started as  abit of a hyperv newbie and it was definitely learning as i went - albeit the servers been running fine for months i just want to pre-empt any issues and of course the whole point of the cluster is to enable us to move machines about for maintenance etc.

any help appreciated

thanks
Lee PepperDirectorAsked:
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NetfloCommented:
If you're clusters hosts are part of the same cluster, live migration should work perfectly. If you've gone and renamed the adaptors, etc this will break your cluster and functionality. You want your infrastructure to be validated and not change the Hyper-V network names afterwords. Changing the Hyper-V network names is like physically separating the network. Same network = same name.

At your stage, as you've renamed the network switches back. I would reboot each cluster host in your cluster so each node is aware of the changes which have been processed, this should be enough to get your live migration working correctly.

Before attempting to validate your cluster, considering your scenario I would recommend exporting all your VM - just in case. Then when you have a moment of downtime, to perform a cluster validation. The validation will take all your resources offline temporarily.

Best of luck!
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Lee PepperDirectorAuthor Commented:
Hi Netflo,
thanks for the reply, ill try and wrangle a maintenance break and shutdown the hyperv clients and then reboot the hosts.

On the validation im sure i renamed them back to the defaults at the start of the project during the setup - purely because if i remember correctly the validation tests kept failing and so i think sort of needed to do that to get them to work. I could be wrong as it was 7 months ago.

Its like they have the original network switch names resident somewhere - i think your right to reboot the hosts in case there is any cached reference somewhere and that might be enough.

I just hope if i run the validation test and then this time it fails - my servers still come up (so the customers still work) , it just breaks the cluster - e.g. business risk is hopefully low!

thanks
Lee
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NetfloCommented:
Just a thought, you can validate your 'network' only and leave all other services, drives, etc online.

Also if the cluster has been validated and if it fails it won't break it per se. It will just tell you that you need to get it to a validated state if you want it to be supported by MS.

I've answered a few questions on EE mostly to do with Live Migration not working, and in most cases its because the validated config has changed and effectively upset the cluster.

You'll be up and running after the hosts reboot.
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Lee PepperDirectorAuthor Commented:
HI Netflo,

I managed to schedule the maintenance work at 5am this morning! - i rebooted the hosts but the live migration still failed. I did re-run validation on network only and it went through them ok but still failed live migration.

then i noticed a technet article about if you change network details after initial setup and suggested a 'refresh virtual machine config' (http://support.microsoft.com/kb/2592237)

i did this on all my servers and then i could do the live migrations !

so thanks for your input it was a great help.

if you know any decent hyper v cluster 'maintenance' guides id be interested to have a look.

regards
Lee
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NetfloCommented:
Glad to hear you finally managed to get your cluster operational.

Have a look at this link: http://technet.microsoft.com/en-us/library/cc731291.aspx

Your best option would be to have a 2012 cluster, where you can use 'node drain' which will perform live migrations for you and drain nodes and then fill back once maintenance is complete.
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Lee PepperDirectorAuthor Commented:
Hi Netflo,

mmm jumped the gun a little - its ok but its not quite 100%, the 2 servers i did a test migrate on did that fine (as in moved hosts) but what i didn't realize is they lost outbound network  connectivity.

so this morning i worked out that by assigning the original 'New Virtual Network' adaptor to them it pinged back into life. (a little task to work out as they are all called the same!)

I have 7 virtual networks - each assigned to a physical adapter (have 2 x quad cards in each host) and they are all named the same 'New Virtual Network'. So i thought i could move them about and as they are named the same it shouldn't matter- the same virtual network name is in use on all three hosts, the same physical NIC as well.

Im wondering if really i need to have 1 virtual network assigned to 1 physical adapter for all 3 hosts and then move them across onto that - but i thought i was 'load balancing' by spreading them across these different virtual networks.

I think i understand what the problem is, i just got to work out best physcial/virtual network config that will mean when a machine is moved about it doesnt matter what virtual network it sits on - on the new host...

thanks
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NetfloCommented:
For your Hyper-V rig, at the bare minimum I would recommend LAN1 - Host which is host exclusive only and LAN 2 - VM which is mapped in your Hyper-V Networking for pass-through LAN connectivity for all your VMs to talk on your LAN. Your environment will work as expected.

Just to give you an idea of scale, I've successfully managed a Server 2008 R2 Hyper-V cluster running 40 VMs, shared across two Hyper-V nodes and all using 1 NIC for VM traffic. It'll work perfectly fine.

Again your LAN 3 can be Live Migration and LAN 4 can be CSV.

See 'scenario 2' for what I'm describing as the bare minimum and validated configuration for your setup: http://ramazancan.wordpress.com/2011/07/25/failover-cluster-network-design-with-hyper-v-how-many-nics-are-required/

Get your setup working then you can scale out and utilise the extended redundancy that your NICs have later.
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Lee PepperDirectorAuthor Commented:
HI Netflo,

i did dedicate 1 physical NIC on each to the management network and then the rest i basically made virtual networks from.

I think i understand what i can do from here - so thanks for your assistance and ill close this off now.

regards
lee
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Lee PepperDirectorAuthor Commented:
very helpful, thanks
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NetfloCommented:
Most welcome and glad to have helped.
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