VSM and VEM on the same host

Unanswered Question
May 30th, 2010

Hello,

I red on N1K getting started guide that you have to take care to install VMS and VME on the same ESX.

It state that you have to avoid to power off VSM, why ? is that true even in active/standby VSM configuration ?

What's up when VEM's lose connection to active VSM ?

I have this problem too.
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Jeremy Waldrop Mon, 05/31/2010 - 03:42

The VSM is not in the data plane, meaning that if the VSM is down traffic flow is not interrupted between VMs and hosts. If the VSM is down you can't make any changes nor can you plug new VMs into the N1KV dvSwitch.

If you deploy the recommended active/standby with 2 VSMs then make sure you create a VMware DRS rule to always keep the 2 VSMs on separate ESX hosts.

The VSM can also live on an ESX host that is part of the N1KV dvSwitch.

Me personally, I like to put the VSM in a port group that lives on a standard vSwitch along with the ESX service console and vMotion vmkernel. Doing it this way makes for a smoother/easier deployment and is a lot easer to troubleshoot when things go wrong.

helenio Mon, 05/31/2010 - 04:05

on N1K (nexus 1000V)getting started guide that you have to take care to install VMS and VEM on the same ESX.

It state that you have to avoid to power off VSM, why ? is that true even in active/standby VSM configuration ?

Jeremy Waldrop Mon, 05/31/2010 - 04:18

The VSM can be on any ESX host in your environment that has the proper management/control/packet VLANs trunked to it.

If the VSM is down you can no longer manage your VM switching environment and you cannot add new VMs to the  N1K distributed switch. If the VSM is down it doesn't interrupt traffic flow because it isn't in the data plane, only the management plane.

If you have an active/standby deployment and the primary VSM goes down the secondary VSM is rebooted and becomse the active VSM, while the secondary VSM is rebooting there will be a few minutes where you can't access the VSM management. Data flow is not interrupted during this failover event though, only management.

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