Re-use VMware ESXi host for Windows?

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ianbutton1
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Joined: Thu May 14, 2015 5:45 am

Re-use VMware ESXi host for Windows?

Post by ianbutton1 »

After moving its guests onto other ESXi hosts, we have simply removed a ESXi 5.1 host, that was in a cluster connected to datastores on 3PAR, from its rack. We want to re-use it as a HyperV host in a Windows cluster, attached to the same FC switch. The other HyperV hosts in the Windows cluster already use the 3PAR, with Cluster Shared Volumes.
We are worried that simply installing Windows and adding volumes to it might corrupt LUNs on the 3PAR (as it might still see the VMware LUNs but try to use them for Windows, or something equally dangerous).
What is the proper decommissioning procedure, please? Should we remove the host from the VMware hostset, and/or unexport the VMware 3PAR LUNs from the old host? Anything else?
Is it good, or bad, to cable the new HyperV host up to the same ports on the FC switch, that it used when an ESXi host?
What are the recommendations regarding zoning?
What about changing Persona - does that bring risks?
All suggestions gratefully received.
TIA
Ian
MammaGutt
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Re: Re-use VMware ESXi host for Windows?

Post by MammaGutt »

You should always remove exports to a host during decomm.

If that is done with vvset to host set, vvset to host or vv to host, would tell you how you have to remove it (remove host from host set, delete vv set export to host or delete vv exports to hosts).

You would also have to redefine the host on 3PAR as ESX use persona 11 and Windows use persona 15.

Not doing anything will never corrupt the LUN on the 3PAR, but Windows can easily bring the volume online and prompt you to format it with NTFS. The result is the same with data loss, but this isn't a 3PAR/LUN issue, but more on how Windows works and what it does.

There is no issue on reusing FC ports on SAN switch, but you might use different host ports for Windows resulting in you needing to redo the SAN zoning for the host.
The views and opinions expressed are my own and do not necessarily reflect those of my current or previous employers.
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Richard Siemers
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Re: Re-use VMware ESXi host for Windows?

Post by Richard Siemers »

Well said.

Proper decommission is critical, especially in a cluster environment like VMware.

Ejecting a ESX host from a production cluster, but not decomission its SAN exports, can cause disaster if the new OS tries to partition all the drives it sees, or, if someone uses a life cycle manager tool to wipe/reset the server prior to repurposing it.
Richard Siemers
The views and opinions expressed are my own and do not necessarily reflect those of my employer.
ailean
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Re: Re-use VMware ESXi host for Windows?

Post by ailean »

Personally I'd do something like this;

1) Take out of cluster and shutdown.
2) Delete the host object from 3PAR (take a note of wwns).
3) If zoning different for Windows vs Vmware hosts update the zones (if using a 7000/8000 3par you might not have enough spare host ports to have done different zones).
4) Rebuild the host and update to current Window cluster level.
5) I'm not sure for Windows but in VMware we'd normally add it to the cluster before presenting shared LUNs, to make sure it's happy.
6) Create the new Windows 3par host object and add to the Windows cluster groups, probably a rescan or reboot after to pick everything up.

I find having any SAN LUNs visible to a host (whether correct OS or not) while installing the OS often complicates things so tend to do that last. Host object is easy to recreate so removing it at the start is a nice clean way to eliminate any chance of old LUNs being exposed.

We'd have to change the zones, the host name and the persona here, due to the way we have things setup. Luckily we only tend to move hosts between Vmware clusters so a little simpler. ;)
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