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Re-install vCenter. Anything to do on Nexus 1000v

stanley_cwy
Level 1
Level 1

We have UCS and Nexus 1000v running in our production. Due to some problem with the vCenter server, we need to re-install the vCenter server.

Would like to know what should we do on the Nexus 1000v as re-installing the vCenter will cause the svs connection to break. Any way to do it without any disruption to the existing VMs?

Please share your experience or comment. Thanks in advance.

17 Replies 17

lwatta
Cisco Employee
Cisco Employee

Its an involved process that will require backing the hosts out of the vDS, migrating to vSwitch, adding everything to the new vCenter and migrating it back to nexus 1000v.

Take a look at the following KB article

http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1020893&sliceId=1&docTypeID=DT_KB_1_1&dialogID=269944173&stateId=0%200%20257014914

Are you having to install everything for vCenter including it's database?

louis

yes. everything including it's database.

looking at the article, there will be some downtime when changing from Nexus 1000v to standard vSwitch. this will be the last option.

Jeremy Waldrop
Level 4
Level 4

Being on UCS you have some options here but need to know what your current configuration is.

how many UCS vNICs are presented to ESXi?

are you using VMware standard vSwitches for management and vMotion and N1KV for VMs?

we have 2 ESXi. with 6 vNICs configured.

4 for production (used for VM) under Nexus 1000v.

2 for vkernal (management & vMotion) under vSwitch.

Great, here is how I would do it with no downtime. I have done this a few times so I know it works.

  1. On one ESXi host create a new standard vSwitch with no uplinks
  2. Create all needed port groups on the new vSwitch
  3. Take 2 of the N1KV uplinks away and uplink them to the new vSwitch
  4. You can then use vCenter Host Profiles to create a new profile from this reference host
  5. One host at a time put it in maintenance mode and apply the profile and exit maintenance mode
  6. After all hosts have the new network config use the Migrate Virtual Machine tool that is on the N1KV vNetwork Distributed Switch within vCenter to migrate the VMs from the N1KV port group source to the VMwre standard vSwitch port group
  7. Now 1 host at a time remove it from the N1KV
  8. You are now off the N1KV and can create a new vCenter
  9. Attached your hosts to the new vCenter
  10. Deploy 2 new VSM instances in the new vCenter and create your port profiles
  11. The 2 free vmnics on each host can then be used to re-attach the hosts back to the N1KV
  12. After all hosts are back on the N1KV use the Migrate Virtual Machine tool to move the VM networking back
  13. After VMs are moved remove the standard vSwitch and uplink the other 2 vmnics to the N1KV

sounds workable... but involve lots of changes, not sure the change request will be approved.

another issue is we only have 2 hosts and it is insufficient resources to handle all VM by 1 host.

thanks anyway for the suggestion...

stanley_cwy
Level 1
Level 1

i just wondering whether we can perform the following:

- Disconnect the svs connection.

- Remove the svs connection configuration.

- Re-configure & re-connect the svs configuration after the vCenter has been re-installed.

my understanding is the Nexus 1000v will still be working if the vCenter is down right? correct me if i'm wrong. thanks.

The problem will be that the vDS config on the hosts will not match with vCenter. The hosts will say they have a stale vDS and you'll never be able to see or modify anything to do with the vDS on the ESX hosts in vCenter.

vCenter can't import old vDS data. When you install a new vCenter the vDS data is completely new and does not match what is on the hosts.

Traffic will continue to flow but the hosts nothing will ever look correct in vCenter and you will not be able to make any changes to VMs or ESX hosts.

Its frustrating I know. We are tying to find a way to export old vDS data and import it back into vCenter.

louis

that is too bad.. if really got to re-do the Nexus 1000v, i'll have to re-host the license right? as the host ID will change.

even better, with only 2 hosts no reason to use host profiles or go into maintenance mode just make the change manualy on each host

Sent from Cisco Technical Support iPad App

no, you can use the same VSMs just redo the svs connection to vcenter

Sent from Cisco Technical Support iPad App

i just wondering whether we can perform the following:

- Disconnect the svs connection.

- Remove the svs connection configuration.

- Re-configure & re-connect the svs configuration after the vCenter has been re-installed.

but the comment from louis says:

The problem will be that the vDS config on the hosts will not match with vCenter. The hosts will say they have a stale vDS and you'll never be able to see or modify anything to do with the vDS on the ESX hosts in vCenter.

vCenter can't import old vDS data. When you install a new vCenter the vDS data is completely new and does not match what is on the hosts.

Traffic will continue to flow but the hosts nothing will ever look correct in vCenter and you will not be able to make any changes to VMs or ESX hosts.

Its frustrating I know. We are tying to find a way to export old vDS data and import it back into vCenter.

no, that will not work. safest option is to migrate to a standard vSwitch, remove hosts from N1KV, rebuild vcenter, recreate svs connection and then migrate back. you can do all of this with no downtime.

Sent from Cisco Technical Support iPad App

For VSM you are fine. You can disconnect and reconnect. It's the ESX hosts that will be stale. You need to first remove them(ESX hosts) from the vDS by migrating everything to vSwitch as was previously stated

The VSM will be fine with a disconnect and reconnect.

louis

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