I have had a number of people request the test flag and one response said it was kicking up errors when used with the CAD service/process. Please note this flag is only needed in the event of a system state restore and you would not (I hope) be using the CAD/Scheduler to restore your system state. So the testflag should only be activated in the dsm.opt in the event you are doing a manual restore of the system state and DO NOT leave it in the dsm.opt as it will affect daily use.
1/24/2018 Update
After waiting for IBM to post an update to this issue I decided I would let you know that IBM has an undocumented flag for this issue that allows the client to restore the System State online rather than work with the PE. Our Windows admins spoke with Microsoft and they state emphatically that they support online system state restores, so is appears IBM does not starting with the 8.1.x client. Here is the flag to allow the SP client to perform online system state restores.
ONLINE_SYSTEMSTATE_RESTORE_ALLOWED
12/4/2018
I wanted to make everyone aware that starting with the 8.1 Windows Client, IBM has deprecated the System State restore process so that any restore attempt will require the use of a WinPE environment. With the 8.1.x client you can no longer do a complete restore of a server within the normal windows environment and will have to make sure you have a compatible WinPE for every Windows Hardware type or environment. This, in my opinion, is a huge break of the software. Although IBM stated that Microsoft does not support online system state restores, Microsoft disagrees. I say this knowing that if you are on a 7.x or earlier version of the client IBM will support you with the system state restore, but as of 8.1 you will be directed to build a Windows PE environment and follow a series of stepto create the necessary disc. The support person I spoke with treated this process as if it should be second nature to any Windows Admin.
We recently were migrating a clients server and in the process the disks were corrupted. The client installed on the new machine was 8.1.2 and when the Windows Admins tried to restore the system state they experienced the following error.
After speaking with support we were directed to the following document by Andrew Raibeck that discussed creating the WinPE disk image with the TSM client code that would allow the offline restore of the System State. We attempted to build the ISO but when the Windows Admin tried to run the dsmc client we experienced the following error:
Who do we call when we experience an error like this in a WinPE environment? IBM or Microsoft? So you have two choices, have a Windows PE available for each hardware type or try using the testflag but understand IBM may support its use. If you were fully aware of this and took precautions what were they? My thinking is that many admins have no idea this is going to bite them and its better you know now than find out the hard way.