How to upgrade ESXi 4.1 to ESXi 5.5?

This is planning in upgrading the VMware virtualization environment to ESXi 5.5. The current setup is 3 ESXi 4.1 hosts, all using DELL PowerEdge Servers, with PowerConnect 6248 switches, and DELL EquaLogic 61xx iSCSI SAN. DELL MD32xx storage also in use. So, each DELL server has 2-pair of iSCSI connections, one to Equalogic, and another one to DELL MD32xx. There are multiple VLANs. All ESXi 4.1 hosts are using Essential plus License.

Now, A new DELL PowerEdge Server is brought in, with 1 PowerConnect 48-port switch, 1 DELL Equalogic 61xx iSCSI SAN. How should I upgrade to ESXi 5.5? Shall I setup a new Virtualization environment with the newly-brought in hardware, and then move VMs over? Or can I straightaway upgrade the existing 4.1 ESXi hosts, and then introduce the new ESXi 5.5 host? the new license for ESXi 5.5 is Standard license.

Please help, appreciate very much. HA, vMotion must be part of the setup.
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Ganesh Kumar ASr Infrastructure SpecialistCommented:
Here is document for Best practices on upgrading VMWare:

Best practices is to : add a new host to existing environment with the newly-brought in hardware, and then move VMs from other hardware.

You cannot upgrade from 4.1 directly to 5.5 instead it can be only through 4.0>5.0 and then 5.5.

Supported upgrades :
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
What you *MUST* do first is Upgrade vCenter 4.1 to vCenter 5.5.

Sometimes, this does not go well (e.g. it breaks), and most decide to create a new vCenter 5.5 Server from new.

See this great Article

I'm not too sure, what the first poster, was discussing.

You can upgrade ESXi 4.1 directly to ESXi 5.5, using the CDROM, Interactively or using Update Manager.

I would also note, that as you are using Dell Hardware, download and use the OEM DELL version from the Dell website.
MichaelBalackAuthor Commented:
Hi both,

Shall i do this way:

1. Setup esxi 5.5 on new hw, and join it to the group
2. Gradually migrate vm to this new host
3. Resetup those old host to esxi 5.5, n join it back to the group ome at atime
4. Ultimately all old hosts resetup with 5.5
5. Either uprade vcenter to 5.5 directly or disjoin all hosts n setup a new 5.5 vcenter; join all hosts to this new vcenter
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Yes, that will work, remember ESXi 5.5 can only be managed by vCenter 5.5.

So I would create a new vCenter 5.5 first, and then remove ESXi 4.1 from current vCenter, add to new vCenter 5.5, and then upgrade.
MichaelBalackAuthor Commented:
Hi Andrew,

ok, have to setup the vCenter first. Any consideration/impact when moving the ESXi 4.1 from the current vcenter?
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
None, VMs will still run and not be affected.

Make sure you do a remove from vCenter Server, otherwise it will complain about still be managed by vCenter at IP Address etc

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MichaelBalackAuthor Commented:
Thanks Andrew, although the whole migration is halfway through, no problem found and I sure the process will work perfectly.
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