Removing disk units from configruation

When we brought in a new machine (8202-E4D) this spring, I put a handful of drives into an IASP for possible use by PowerHA. A recent business need came up where I would like to return these drives to *SYSBAS. I have varied the IASP offline. In SST, under Remove Units from Configuration, when I put '4' on one of them to remove them, I get this message:

To proceed, the system must perform directory recovery, which
may take a significant amount of time. The system may appear
inactive during this time.

My question is first, do I want to 'Remove Units from Configuration' to accomplish this? And 2nd: if this is part of an ASP that is offline (and there was never anything on there in the first place) how long can 'directory recovery' take? Will it actually make the system unresponsive during this? Whatever 'appear inactive' means...

Thanks
Dana


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