{"id":14509,"date":"2013-05-01T13:00:00","date_gmt":"2013-05-01T12:00:00","guid":{"rendered":"https:\/\/aidanfinn.com\/?p=14509"},"modified":"2013-05-01T13:00:00","modified_gmt":"2013-05-01T12:00:00","slug":"another-ws2012-hyper-v-converged-fabric-design-with-host-guest-iscsi-networks","status":"publish","type":"post","link":"https:\/\/aidanfinn.com\/?p=14509","title":{"rendered":"Another WS2012 Hyper-V Converged Fabric Design With Host & Guest iSCSI Networks"},"content":{"rendered":"

Back in January I posted<\/a> a possible design for implementing iSCSI connectivity for a host and virtual machines using converged networks.  <\/p>\n

<\/p>\n

In that design (above) a pair of virtual NICs would be used for iSCSI, either in the VM or the management OS of the host.  MPIO would \u201cteam\u201d the NICs.  I was talking with fellow Hyper-V MVP Hans Vredevoort (@hvredevoort<\/a>) about this scenario last week but he brought up something that I should have considered. <\/p>\n

Look at iSCSI1 and iSCSI2 in the Management OS.  Both are virtual NICs, connecting to ports in the iSCSI virtual switch, just like any virtual NIC in a VM would.  They pass into the virtual switch, then into the NIC team.  As you should know by now, we\u2019re going to be using a Hyper-V Port mode<\/a> NIC team.  That means all traffic from each virtual NIC passes in and out through a single team member (physical NIC in the team).<\/p>\n

Here\u2019s the problem: The allocation of virtual NIC to physical NIC for traffic flow is done by round robin.  There is no way to say \u201cAssign the virtual NIC iSCSI1 to physical NIC X\u201d.  That means that iSCSI1 and iSCSI2 could end up being on the same physical NIC in the team.  That\u2019s not a problem for network path failover, but it does not make the best use of available bandwidth.<\/p>\n

Wouldn\u2019t it be nice to guarantee that iSCSI NIC1 and iSCSI NIC2, both at host and VM layers, were communicating on different physical NICs?  Yes it would, and here\u2019s how I would do it:<\/p>\n

\"image\"<\/a><\/p>\n

The benefits of this design over the previous one are:<\/p>\n