Failover cluster recommended networks

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Failover cluster recommended networks

Jon Marshall 81

Hi all

I am in the process of setting up a failover cluster with hyper-v and am just sorting out the required networks.

For storage we are using iSCSI so they are 2 x 10Gbps connections not teamed etc.

For the other networks I have a team and the recommendation is to use -

1) management network

2) Live migration network

3) CSV/Heartbeat network **

** I have read that actually there is no such thing as a specific heartbeat network and the heartbeat can actually run across all the vlans/networks.

The question I have is around 3). The Management network will be cluster and client, the Live Migration will be cluster only and you can tell FCM which specific network to use for Live Migration.

What I can't work out is how does FCM know to use the CSV network for CSV traffic ? This network will be marked as cluster only, so does it use it because -

the management is cluster and client so it ignores that
the storage are cluster only but they are storage specific
the Live migration has been specifically marked for that purpose

so the only cluster only network left is 3) the CSV/Heartbeat network.

Put simply how can you know that the CSV/Heartbeat network is actually being used.

Jon

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Eric Siron 1,586 MVP

The cluster will send heartbeat, config, CSV data, etc. across any network marked as "Cluster" or "Client and Cluster" in FCM's "Networks" section.
The best thing is usually to leave them all enabled for cluster traffic and let the cluster and SMB figure out what to do. If you have performance traces showing negative impact of SMB on non-SMB traffic or you just don't like letting the computer decide, set the other networks to not allow cluster traffic. You do not need to enable cluster traffic on networks that you only want to use for iSCSI or LiveMigration.

Jon Marshall 81 Reputation points

2021-08-16T12:53:26.837+00:00

Thanks for the response.

So if the cluster uses any of the networks is there really any point in creating the CSV/Heatbeat vlan, that's really what I am trying to work out.

I understand the need for management vlan and the Live Migration vlan and obviously the 2 storage vlans for iSCSI but if the cluster just works it out then why does everyone recommend that CSV vlan if the cluster could just as easily use the management or Live Migration vlan for CSV traffic.

Just not really understanding why it is a recommended vlan/network if the cluster may not even use it.
Jon Marshall 81 Reputation points

2021-08-17T17:45:27.223+00:00

Just a quick follow up on this.

I actually found this link written by you I believe :)

Based on that and considering I only have 2 x 1Gbps in my team for the vswitch I think I am just going to have -

1 x management network
1 x cluster network

because as you say Live Migration will use both anyway so it is purely optional and 2 networks with 2 physical NICs should be fine.

Many thanks for response here and the doc, very helpful.
Eric Siron 1,586 Reputation points MVP

2021-08-17T19:49:24.527+00:00

Early documentation was not clear and led many people to believe that CSV traffic was distinct from other cluster traffic. Not everyone has gotten around to updating their knowledge.

I create one logical network per general-use 10Gb+ physical adapter. If I have 2x 10GbE, then I make 1 management + 1 Live Migration network, both enabled for cluster traffic with the Live Migration network set as preferred for Live Migration. If I have 4x 10GbE, then I make 1x management network and 3x cluster networks. If I have > 4 general-purpose 10GbE adapters then I start asking why I have > 4 10GbE general-purpose adapters because that money could have bought more memory. I try to keep storage traffic on dedicated physical adapters, but when I can't, I just add them as logical networks with no change to my other procedure.

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