Using LR Classic, copied LR catalog to new disc, how to locate missing files in LR on the new disc without doing it one folder at a time?

Every photo file that is imported in a Catalog stores a remembered file path. The Folders panel is a summary report of all of these remembered file paths - all coming from info within the Catalog. These file paths initially derived from, and hence necessarily matched, an actual file location at import time.

If that actual file location is then changed externally, the remembered file path within the Catalog (which has persisted the same, unaware) will no longer match and the image / folder seen within the Catalog reports that it has now lost connection with its external source.

The question “how do I get the LR Catalog to find the images on the new disk” requires some clarity and care, It’s important NOT to start moving stuff around individually OR to delete stuff, or to reimport anything, or to use Sync Folder. The only operation needed is to readdress (update) the Catalog’s remembered file paths leaving everything else as it is.

This can be done easily in bulk, provided the transfer of files and folders was also done in bulk and without changing the subfolder arrangement within that. Provided that is so, readdressing any top level folder also readresses all of the subfolders and images nested within this. You can make such a parent (containing) folder show up inside the Catalog Folders panel, if it is not currently visible - using “Show Parent Folder” on one of the folders that you do see.

So you get to a top point of management with lots of folders nested inside (this does not need to go right up to the root level of the drive volume). All of this shows offline, but can be reconnected so far as the Catalog is concerned, using “Find Missing Folder” onto your top point of management folder and browsing to the corresponding folder in the new drive location.

More Info…  SSHD with original DNG has 175,000 images.  LR Folders panel sees 3800, because those are the folders that I have reconnected by hand.  How do I get LR to connect to the rest of the images on the SSHD.  There has to be a better way.  It will take forever this way.  

More info… I have done this before and not had this issue.  I am missing something.  In the past, I feel like I reconnected 1 folder and LR was smart enough to know that all the images were on this new HD.    🤔.   To simplify… How do I get the LR catalog to find the new HD of original images in one (or 2) steps?  Tried the”Find all missing files” route but then what?  It directs me to the ext HD which has 175,000 images on it.  The same HD within LR only has a little over 1,000 images.   How do I show LR catalog to see the entire ext. HD of original RAW files?   What am I missing?  TIA.