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We recently purchased new VM hosts, and we're trying to upgrade our current ESX 4.0 environment (3 hosts, running about 15 VMs and VCenter) to the new hosts which are running ESXi 5.0.

Do I need to update my existing hosts to ESXi before I am able to migrate? I'm currently unable to add any of the new hosts to the existing vcenter - vSphere client, probably due to the difference in version.

Any thoughts or starting points? most of the information i've come across so far is for upgrading hosts, but not for migrating to new hosts of a different version. Thanks in advance for any info or links provided.

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Does anything happen in particular when you try adding the clients to 5.0? Errors? – Nathan C May 17 '13 at 18:28
You can't manage vSphere 5 hosts from vCenter server 4, AFAIK. The vCenter server needs to be upgraded. – joeqwerty May 17 '13 at 18:54
Which licensing tier do you have? – ewwhite May 17 '13 at 19:00

Upgrade vCenter first... A newer vCenter can typically see and connect to older ESX/ESXi hosts. You should be at version 5.1 at this time.

  • Do your virtual machines live on shared-storage? If so, you can disconnect them from the old cluster and add to the new... That's one option. Another is to join everything and migrate between.

  • Do you intend to continue using your old hosts? That will impact how you approach the above.

  • You bought hardware and (possibly) licensing... What was your original migration plan?

I'm in the middle of such a move now. There are plenty of other considerations:

  • vSphere 4.0 didn't have thin-provisioning. This migration will allow you to reclaim some of that space if you change datastores.
  • VMware tools will need to be upgraded on all virtual machines. This can be done on the fly in most cases.
  • The VM hardware versions will also need to be changed in order to take advantage of the capabilities of the newer hypervisor. This will require a VM power-off.
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You're not really upgrading your hosts, you're replacing your hosts. The first step is always to upgrade your vCenter server first.

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