In case one of your Farm's servers have been patched lately (only one server for example, and no Configuration wizard ran) and you need to revert the changes...
You cannot uninstall the SharePoint Patches…
The safest way for this kind of issue to resolve, is to: backup the farm, remove this server from the farm, uninstall SharePoint, re-install with correct updates and join the server back to the farm...
As a second “safe” option: install the same fixes to the other SPS servers in the farm and run the Configuration Wizard on each server..
On the other hand, the following 2 methods are supported but they involve quite a risk..
If no PSconfig was ran and you have a backup of the VM (i.e. by using DPM) from a previous time prior to he incident, you need to check the DB version. You need to know the Patch level where the DB was on that previous state of the VM...
Was the DB backup and VM snapshot taken at the same time?
It’s hard to confirm the steps, so whatever the VM state is (Patch Level), you need to make sure that the same DB is also restored back to the same level as previously.
For example: If you have NOT run PSConfig and the DB shows i.e. June CU > you need to make sure that you have a VM backup of the June CU and revert it back…..
Most importantly, the consistence between the VM backup and the DB should be same.
So these are the additional 2 options you have:
Option#1: You should have taken a VM backup and the DB backup at the same time > and that will be the best restoring point for you.
Option#2: Restore the VM backup and restore a DB backup which was taken prior to the VM backup and attach this DB to the Site.
Note on supportability of reverting the VM to a previous point in time:
The snapshot feature of Hyper V and other virtualization products are not supported for SharePoint farms.
Snapshots in farms with more than one server, may cause inconsistencies (sync issues) when rolling back to a previous snapshot on one of the servers in the farm, which may result in data corruption.
It is not recommended to use snapshot to backup data in production environment.
I would suggest you considering using other tool such as System Center Data Protection Manager to backup the SharePoint Farm on such scenarios.
More information you may find here: http://technet.microsoft.com/en-us/library/cc261687.aspx
Do not use snapshots in a production environment (from http://technet.microsoft.com/en-us/library/hh295699.aspx)
Virtual machine snapshots are file-based snapshots of the state, disk data, and configuration of a virtual machine at a specific point in time. Do not use snapshots in a production environment for the following reasons:
- Microsoft SharePoint Server uses timer jobs extensively; snapshot latency adversely affects time-sensitive operations and can result in data corruption or data loss.
Important Do not configure a virtual machine to save state during shutdown as this is also affected by latency.
Snapshots reduce virtual machine performance and increase physical storage requirements.