vCon Placement in UCS

[Dominic Foley]

Hi there,

I have a question in regard to placement of vnic's in UCS specifically to the vCon assignment.

In my system I have B200M3 servers with the UCS Vic1240+mlom port expander card.

What I'm wondering is how many vCon's I have in my system?  From what I have read, each vCon is the virtual representation of the physical adapter, so in my case I would have a single vCon.  This would make sense, because when I look at where the system has placed my vnics, they are all associated to vCon1.

However, when I look at the "Modify vNIC/vHBA Placement" and do a specify manually, I see four vCons (vCon1 - vCon4).  Are these there by default, and/or should I be able to use vCons 2-4?  If I am able to, then I wonder why the system has only chosen to use vCon1 ?

Any assistance in this understanding would be gratefuly received!

Thanks

Dominic

[Walter Dey · Accepted solution]

vcon is equivalent to physical I/O adaptor; in your case VIC-1240 + port expander is 1 I/O adaptor, therefore you have only one vcon.

the fact that 4 vcon's appear, has to do with the fact, that UCS C-Series servers can have up to 4 I/O adaptors; B-Series servers are limited at the moment to 2 I/O adaptors.

[Dominic Foley]

Great thanks very much, it's as I thought, just wasn't sure why I saw 4x vCons, but now I know.

[Boudewijn Plomp]

The only question remains is; Suppose you always want to have a specific order with one adapter, but once you move a Service Profile to another server with two adapters, you want them to be spread amongst these two adapters in a round-robin fashion. For example:

One Adapter: vCon 1:

1 - iSCSI_Eth0

2 - iSCSI_Eth1

3 - Eth0

4 - Eth1

5 - VM_vEth0

6 - VM_vEth1

Now if you move above configuration to another server with two adapters:

First Adapter: vCon 1:

1 - iSCSI_Eth0

2 - Eth0

3 - VM_vEth0

Second Adapter: vCon 2:

1 - iSCSI_Eth1

2 - Eth1

3 - VM_vEth1

Is this correct? I think I have to alway spread them amongst two vCons or select automatic placement, right? With boot from iSCSI this can be tricky.

Boudewijn

[Walter Dey]

I usually recommend the following

1) use different service profiles for blades with one resp. two I/O adaptors

2) never use automatic vnic/vhba placement, do it manually

3) do you really need 2 adaptors ? in most environments one is enough (VIC-1240 plus extender counts as one)

4) avoid any rathole discussion about the MTBF resp. single point of failure of the single I/O adaptor; I have never seen a failing I/O adaptor, and btw. there are other single point of failures on the blade; thats why you would scale horizontally, and setup e.g. a DRS cluster

[Boudewijn Plomp]

I fully agree. I don't need or want two adapters. In our case we use a VIC 1240 + port expander. But of course you want to have the correct settup in case of scalability, blade/server replacement and so on. Just curious about it.