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Assigning NIC in Hyper-V R2

quadrumane
quadrumane used Ask the Experts™
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According to Netapp we should assign a NIC for CLUSTER on a dedicated network and another NIC for LIVE MIGRATION on a dedicated Network.  In other hands, most of the time the configuration Ithat seems to be recommanded  does have only one NIC for both (CLUSTER NIC is the same as LIVE MIGRATION)

What is your advice ?  I can have as many NIC as I need (10 or 12) on the servers.  But I found this information only on the netapp web site.  thanks



BP #1: Network Configuration in Hyper-V Environments

There are two important best practices to mention when it comes to network configuration:

    * Be sure to provide the right number of physical network adapters on Hyper-V servers.
    * Take advantage of the new network features that Hyper-V R2 supports if at all possible.

Physical network adapters. Failure to configure enough network connections can make it appear as though you have a storage problem, particularly when using iSCSI. Smaller environments require a minimum of two or three network adapters, while larger environments require at least four or five. You may require far more. Here’s why:

    * Management. Microsoft recommends a dedicated network adapter for Hyper-V server management.
    * Virtual machines. Virtual network configurations of the external type require a minimum of one network adapter.
    * IP storage. Microsoft recommends that IP storage communication have a dedicated network, so one adapter is required and two or more are necessary to support multipathing.
    * Windows failover cluster. Windows® failover cluster requires a private network.
    * Live migration. This new Hyper-V R2 feature supports the migration of running virtual machines between Hyper-V servers. Microsoft recommends configuring a dedicated physical network adapter for live migration traffic.
    * Cluster shared volumes. Microsoft recommends a dedicated network to support the communications traffic created by this new Hyper-V R2 feature.
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Commented:
Dedicated NICs are always preferred. Even a small installation of Hyper-V recommends 1 NIC for the VMs and 1 NIC for administration/remote desktop..

Author

Commented:
Yes that I know.  I already have 4 NICs assigned to the VM network, 1 NIC assigned to the Management, 1 NIC assigned to CSV and 1 NIC assigned to Live Migration which is the same NIC used for the Windows clustering.   I just don't understand why they've been adding another NIC called LIVE MIGRATION as the Cluster NIC will be used for LIve Migration.

Commented:
There is no reason why you can't use cluster nic for live migration. Its a recommendation/suggestion/good idea, not a pre-requisite/mandotory requirement.

These are worth a look.
http://www.savilltech.com/videos/2008R2Networks/2008R2Networks8006001mbps.wmv
http://www.savilltech.com/videos/LiveMigration/LiveMigration640480.wmv

Regards,
Shahid

Commented:
It really comes down to what you can afford and how large the environment is. You can configure the NICs in so many ways, even connect each host via separate NIC(s) and so on and so forth.

In OUR production environment, we have 2 hosts, each with 2 built-in NICs each. We use both NICs on each host for the VMs, no dedicated for management or anything like that. The hosts are running 6 and 7 VMs respectively, balanced among the 2 NICs available per host (so roughly 3 VMs per NIC).

This has worked without any issues, but is NOT considered a "best practice" tho.. But it works.

My advice - keep it simple. Don't make it too complicated either.

Author

Commented:
I understand.  But how the cluster NIC and the Live Migration NIC works together ?  Each NIC is on a dedicated subnet.  So what is the purpose of using a dedicated Live Migration NIC as HV in HA will select only one NIC for Live Migration (by default it will be the CLUSTER NIC)

Thanks again

Commented:
I believe, you are under the impression that dedicated NIC for Live migration is a non configurable item. Not true. You can specify which and how many NICs can be used for Live migration. You can read about it under "Configure cluster networks for live migration" section in the following link.
http://technet.microsoft.com/en-us/library/dd446679(WS.10).aspx

By dedicated subnet, I assume you are saying Private Network where communication is limited to only nodes of the cluster and outside world has not idea of the subnet.

Live migration is configured and performed using failover cluster management mmc. It is transparent to hyper-V, as VM is a unit of clustering in this case. The following link is also recommended. Also give it a look.
http://blogs.technet.com/b/askcore/archive/2009/12/10/windows-server-2008-r2-live-migration-the-devil-may-be-in-the-networking-details.aspx

Regards,
Shahid

Author

Commented:
Sorry I'm in vacation I haven't checked my email.  

Yes I have a private network for the CLUSTER NIC, another private network for CSV and another one for Live Migration.  In the event that something goes wrong on a host, how Live Migration will be done ?  I just don't know if all NICs will be used to migrate.

Thanks again
Commented:
In my last post I gave you the link
http://technet.microsoft.com/en-us/library/dd446679(WS.10).aspx
It particularly instruct, How you can dedicate the NIC(s) to LM. For the sake of completion, I am copying the relevant part from the link.

Configure cluster networks for live migration
Cluster networks are automatically configured for live migration. You can use Failover Cluster Manager to perform this procedure.

To configure a cluster network for live migration
1.In the Failover Cluster Manager snap-in, if the cluster that you want to configure is not displayed, in the console tree, right-click Failover Cluster Manager, click Manage a Cluster, and then select or specify the cluster that you want.

2.Expand Services and applications.

3.In the console tree (on the left), select the clustered virtual machine for which you want to configure the network for live migration.

4.Right-click the virtual machine resource displayed in the center pane (not on the left), and then click Properties.

5.Click the Network for live migration tab, and select one or more cluster networks to use for live migration. Use the buttons on the right to move the cluster networks up or down to ensure that a private cluster network is the most preferred. The default preference order is as follows: networks that have no default gateway should be located first; networks that are used by cluster shared volumes and cluster traffic should be located last.

Live migration will be attempted in the order of the networks specified in the list of cluster networks. If the connection to the destination node using the first network is not successful, the next network in the list is used until the complete list is exhausted, or there is a successful connection to the destination node using one of the networks.

Note
When you configure a network for live migration for a specific virtual machine, the setting is global and therefore applies to all virtual machines.

If you have more than one cluster network listed in Network for live migration, you should change the priority order to avoid having live migration and Cluster Shared Volumes use the same network.

Hope that helps.
Regards,
Shahid

Author

Commented:
Great answer thany you very much

Author

Commented:
This answer helped a lot