Best Practices for vMotion QoS in N1kv and UCS?

Unanswered Question
Aug 28th, 2010

Hi,

I'm looking at a few technical documentation on what's the recommended way to provide QoS to vMotion.

From VMWare's website on vSphere deployment with N1kv,

They are using

policy-map type qos vmotion

     class class-default

          police cir percent 30 bc 200 ms conform transmit violate drop

This rate-limits vMotion traffic to 3Gbps and excess traffic will be dropped.

Would this be better if I were to use:

policy-map type qos vmotion

     class class-default

          police cir percent 30 bc 200 ms conform set-cos-transmit 4 exceed drop

policy-map type vethernet vMotion

     switchport access vlan 900

     service-policy type qos in vmotion

     pinning id 0

I'm marking vmotion traffic with a CoS of 4 and pin it to Fabric-A. I will have my management VLAN pinned to Fabric-B.

Also, do I need to configure QoS settings in UCS as well?

For the upstream switch, if I'm using a Catalyst 3750, would it be sufficient just to do a mls qos trust cos?

Appreciate your advice.

Thanks..

I have this problem too.
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Nethaji Vinobaji Wed, 09/01/2010 - 23:58

Steven,

Yes. You can use the modified QoS policy which changes the COS Values.

We need to do some more configuration in Fabric Interconnect for the COS Values that are modified by Nexus 1000v to keep it as it is.

The M81KR adapter works in a “no trust” QoS model which means that it will overwrite the CoS value set by an upstream entity (Nexus 1000v for example). For Nexus1000v deployments, it is highly recommended to do the CoS marking at the Nexus 1000v level. This means changing the QoS model to “trust” on the M81KR.

To create a QoS policy to achieve this, look into the attached file. We need to have option "Full" enabled in it.

Here are further details about this configuration from UCS Manager help:

Host Control field

Whether Cisco UCS controls the class of service (CoS). This can be:

None—Cisco UCS uses the CoS value associated with the priority selected in the Priority drop-down list regardless of the CoS value assigned by the host.

Full—If the packet has a valid CoS value assigned by the host, Cisco UCS uses that value. Otherwise, Cisco UCS uses the CoS value associated with the priority selected in the Priority drop-down list.

Regards

Nethaji V

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