Handling vCenter Server Migration failure scenarios

If a migration fails or you wish to roll back a successful migration then the basic steps are as follows:

1 Shutdown the Appliance 6.0 that has resulted from the migration

2 Power on the original source Windows  5.5 machine

3. The Windows machine will have lost it’s trust with the Active Directory Domain so you may need to log into the Windows machine as a local Administrator and re-join the Active Directory Domain and reboot the Windows machine.

Note: This is because the resulting vCenter Server Appliance 6.0 will have overwritten the Windows vCenter computer account on the AD.

Important: If you have other solutions that have been upgrade for compatibility with vSphere 6.0 these may cease to work after the rollback and would need to be rolled back themselves. This includes ESXi 6.0 as this is not manageable from a vCenter Server 5.5. Also be careful that you do not have Virtual Machines running Hardware Version 11 as these VMs cannot run on ESXi 5.5 or older.

I’ll go into a little more detail on different typologies as the larger and more distributed the environment the more caution and planning is needed

Rolling back a vCenter Server with Embedded SSO

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If you have performed or attempted to perform a migration of a Windows vCenter Server 5.5 with an Embedded SSO and you wish to roll back the migration then you need to perform the following:

1. Shutdown the vCenter Server Appliance 6.0 that has resulted from the migration

2. Power on the original source Windows vCenter Server 5.5

3. The Windows machine will have lost it’s trust with the Active Directory Domain so you may need to log into the Windows machine as a local Administrator and re-join the Active Directory Domain and reboot the Windows machine.

Rolling back a single PSC Appliance to an external SSO

If you wish to roll back the external PSC Appliance 6.0 back to external Windows SSO 5.5 you need to perform the following:

1 Shutdown the PSC Appliance 6.0 that has resulted from the migration

2 Power on the original source Windows SSO 5.5

3. The Windows machine may have lost it’s trust with the Active Directory Domain so you may need to log into the Windows machine as a local Administrator and re-join the Active Directory Domain and reboot the Windows machine.

Important: If you roll back the PSC Appliance 6.0 to Windows SSO 5.5 you must also roll back all vCenter Server Appliance 6.0 instances using this PSC to their Windows vCenter Server 5.5 instances using the same process. A vCenter Server 6.0 cannot run with an SSO 5.5.

Rolling back a vCenter Server with a single external SSO

Performing a roll back of a vCenter Server with a single external SSO gets a little more complicated.

Solution Users are different between vSphere 5.5 and vSphere 6.0.

vSphere 5.5 solution users take the form vCenterServer_ABCDEF.

vSphere 6.0 solution users take the from vpxd-ABCD1234-EFGH5678

Lets say our SSO 5.5 migrates successfully to a PSC Appliance 6.0.

At this point our Windows vCenter 5.5 will continue to work as normal.

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When the Windows vCenter 5.5 is being migrated to 6.0 Appliance, part of this process will delete the original 5.5 Solution Users from the Migrated PSC Appliance 6.0 and create new vCenter Server 6.0 Solution Users.

If we have a failure in migration after this point, and we roll back the Windows vCenter 5.5 – it will be unable to communicate with the PSC as it’s 5.5 Solution Users will have been overwritten with 6.0 Solution Users.

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If you have taken a snapshot of the PSC Appliance 6.0 after it was migrated but before beginning the vCenter Server 5.5 Migration then you can just revert that snapshot to get back to a scenario where the PSC Appliance 6.0 contains the vCenter Server 5.5 solution users.

If there is no snapshot, you will need to roll back the  PSC Appliance 6.0 and start again from the beginning.

Rolling back a replicating PSC Appliance to an SSO

It is not supported to have a mixture of PSC 6.0 replicating with SSO 5.5, nor is it supported to have a mixture of Windows based SSO/PSC and Appliance based SSO/PSC in the same SSO Domain.

If you need to roll back any PSC Appliance 6.0 to Windows SSO 5.5 then you should roll back all PSC Appliance 6.0 instances in the SSO Domain to Windows SSO 5.5 using the standard process of:

1 Shutdown the Appliance 6.0 that has resulted from the migration

2 Power on the original source Windows  5.5 machine

3. The Windows machine will have lost it’s trust with the Active Directory Domain so you may need to log into the Windows machine as a local Administrator and re-join the Active Directory Domain and reboot the Windows machine.

Important: If you roll back the PSC Appliance 6.0 to Windows SSO 5.5 you must also roll back all vCenter Server Appliance 6.0 instances to their Windows vCenter Server 5.5 instances using the same process. A vCenter Server 6.0 cannot run with an SSO 5.5.

Rolling back a vCenter Server  with a replicating external SSO

The process for roll back when you have one or more vCenter Servers that are connected to PSCs that are replicating to other PSCs in the same SSO Domain is the similar to what we spoke about in the “Rolling back a vCenter Server with a single external SSO” section above.

You need to be careful and snapshot every PSC in the SSO Domain before you begin each vCenter Server Migration. Otherwise if you have a vCenter Server migration failure and/or you need to roll back a vCenter Server Appliance 6.0 to Windows vCenter Server 5.5 you would need to also roll back every PSC Appliance 6.0 in the SSO Domain.

Take the example of two Windows SSO 5.5 and two Windows vCenter Server 5.5.

We would first migrate the first Windows SSO 5.5 to a PSC Appliance 6.0.

Snapshot the first PSC Appliance 6.0.

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Next migrate the second Windows SSO 5.5 to a PSC Appliance 6.0.

Snapshot both PSC Appliance 6.0 instances now.

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Next migrate the first Windows vCenter Server 5.5 to a vCenter Server Appliance 6.0.

Snapshot both PSC again.

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Now lets say we attempted a migration of the second Windows vCenter Server 5.5 but it failed, for whatever reason.

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If we were to now power on the Windows vCenter Server 5.5 that failed to migrate the services would fail to start due to the incompatible solution users we spoke about above in “Rolling back a vCenter Server with a single external SSO

If we had not performed the iterative snapshot process we would have to roll everything back. If we have been taking iterative snapshots of the PSCs after each migration task, then all we need to do is revert all PSCs back to the snapshot point taken immediately before starting the migration of the Windows vCenter Server 5.5 that failed to migrate successfully.

Power back on the Windows vCenter Server 5.5 that failed to migrate and re-join the AD Domain.

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Now we are back to a point where both PSCs have migrated successfully, the first vCenter has migrated successfully and the second vCenter has not yet been migrated.

We can troubleshoot and try identify why the second Windows vCenter Server 5.5 failed to migrate and go again without needing to roll back the entire environment.

 

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